Is Parasound on to something? Or, How important is crossover management in preamps?

How important is crossover management in mid-fi receiver?

I auditioned Parasound separates yesterday — P6 and A23+ and the dealer emphasized how useful it would be to be able to control the crossover *both* for the subwoofer (I have a Rel 328) and the bookshelves (TBD, but I'm looking at Dynaudios and Salk WOW1's). Not many preamps have this, and I'm wondering how important it is. I'm also quite interested in PS Audio's separates (Stellar Gaincell + S300) but they do not have these, nor do they have tone controls.

So how valuable is Parasound's controls? What is the significance (positive or negative) control over the crossover — especially of the *main* speakers themselves? The positive, I read, is that it (a) allows mains to do a more precise job by relieving them of the burden of the bottom end, and (b) it increase the efficacy of the power amp in driving the mains. Is there a negative? Is there something "improper" about limiting the demands on mains, especially given their designed frequency range?

As you can see, the answer to this question helps determine whether Parasound has a major value-adding feature in these crossover controls.

Obviously, at the end of the day, auditioning pre's and poweramps (or integrateds) is crucial, as is match to speakers, etc. But if this feature is very important for fitting sub and mains together — and fitting speakers to room environments — then it will help me weigh the Parasound or any other preamp with this feature.

P.S. To those who keep seeing my newbie questions, I hope they're not irksome. I'm posting so often because I'm researching purchases for a whole system, of some cost, and so I'm really digging into these questions about all aspects. And I'm having a blast.
Having a high pass filter is useful when incorporating a subwoofer as it keeps the lower frequencies out of the small bookshelf speakers. It's actually useful even if you don't  have a subwoofer as sometimes small speakers can get boomy or distorted in the woofer if driven a little loud. I would take the Parasound combo or a Parasound  hint 6 which is an integrated that's  these two put together over the PS Audio. The PS audio amplifier is good but that gain cell dac measures lousy. 
Thanks. I’ve written to PS Audio to ask if they have a technical reason not to have this on their unit. I’ve read about the measurement issues, but so many people think it sounds great I’ll probably try it out.
You are conflating a couple of things.

Adding a high pass filter to your mains does reduce the load on the amp, and does make them easier to integrate with a sub, but the Parasound lets you do that without an external crossover. This is to me a big convenience and simplifying feature.

The alternative is you route everything through an external crossover, often in the subwoofer.

Another advantage here is you can use a DSP based EQ on the sub alone, without having your mid/treble frequencies routed through it, they stay pretty much pristine.

If you're upgrading, look for integrated amps first. Ignore features like crossovers. In fact ignore all specifications entirely. Forget watts per channel. Forget whatever nonsense you heard about "matching". Focus on how it sounds. Period. 

Now go back and read the first paragraph again, only this time replace "integrated amps" with speakers.

Now go back and read it again, only this time replace "speakers" with turntable. CD Player. Speaker cable. Power cable.

Got it?

Buy whatever sounds the best.

Oh, and since you said this is for a new system "of some cost" take whatever that number is, divide by 5 for the 5 things you need (source, amp, speakers, cables, and tweaks- cones, rack, shelf, etc) and use that as your cutoff as to what to audition.
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Thanks, Erik. It sounds like all things being otherwise equal, the Parasound feature is a plus.
Thanks, Millercarbon. It seems like if everything sounds good, then the crossover is a plus. (I never said I wanted to make the decision without making listening the highest priority. That would make me a technophile gear head. But I like music.) The division into fifths is something to consider. Thanks for mentioning it.
Here's the take from PS Audio sales. I asked them why their stuff didn't have what Parasound did.

The reply: "We believe handling the crossover is actually detrimental to the sound quality. When a speaker designer finalizes a design for a speaker they have typically done so very carefully. A large part of this process is the crossover itself. So it’s a little bold to believe we can set a better crossover point than the person who designed it."

So, I'm surprised that Parasound, which gets good reviews and seems well-respected would do something so detrimental to the sound quality. Seems gimmicky and non-audiophile to do that. 
Someone has to control the crossover point.  As you pointed out above, it can be convenient to have the option in a preamp, but it's also more circuitry that could be done better with a separate component or within the speaker itself.  I don't see any sense in which it is wrong, and certainly there are some situations/gear in which it could sound better than not using it.  If not, why would they ever have put in the feature. 

Hell, if you really want to control the crossover you can put a Pass Labs XVR1 after your preamp, buy the gear to biamp/triamp and then pull all the inductors/caps/resistors out of your speaker and connect your amps directly to the drivers.  That'd probably sound better once you find all the correct crossover values and levels, but it would potentially double the cost of your system and you'd have to spend many many hours working with the XVR settings.  A first order crossover?  Second?  Fourth?  How many poles do you want in your LP filter?  Plenty of people do that, but they're mostly over on DIYAudio, not here on Agon.  
What did you think PS Audio Sales was going to tell you when you asked why they didn't have the features the Parasound did? If you use a sub with small monitors you need some way of sending the low frequency to the sub and the mid/ high to the monitor there might be better ways than having it in the preamp but unless you want to spend more money and time using crossovers in the pre is effective. 
@cal3713 Good points. The only other reason they might have put the feature in, besides the one you state, is that customers demanded it, despite the effect on sound quality. What I'd like to find out from them, is whether they believe they've pulled it off in a way that makes a minimal/negligible impact. And you're right that I don't want to go that crazy with DIY audio! I'm just trying to determine whether this feature is important — all other things being equal — contingent upon the effect is on sound quality.

@djones51 I suspected they'd say something defending their product (of course!) but I didn't know what they'd specifically say. Also, I am a charitable guy; they might have had some additional reasons I had not considered. Instead, they made an argument based on not messing with the speaker's design, as if every speaker's design would contribute to all rooms, uses, components, etc. If folks here are right, that is specious reasoning. The fact they committed that to print tells me something (maybe not much) about the company more generally. It helps with my purchasing decision.
I don't think PSA's argument is specious at all.  When you change the crossover point, you really are arguing with the speaker designer.  Not that the Parasound feature is likely to be used for anything other than sub integration.  It's also a rare feature, so I don't think PSA was being defensive at all.  Most subs are active and come with a built in crossover that allows you to integrate with your main speakers, so sending them a full signal is normal and expected.  The passive ones expect you to pair them with a subwoofer amplifier that also has gain and crossover controls, also expecting a full range signal.  In both of those cases skipping that circuitry (which is probably coming from a $200 plate amp) and relying on the Parasound probably will improve the crossover quality.
Some horrible advice given by millercarbon. Will lead to worse results. 
Look for Integrated first
Ignore specs, i.e. wpc
Average cost of system elements

Follow that advice and odds of attaining mediocre sound are high.  :(

X-over in sub
Pay attention holistically to specs
NOT average costs! 40% on speakers,  10% on cables, rest on electronics ZERO on tweaks.

OBVIOUSLY system components synergy/matching is critical. 

Not interested in arguing my advice. Pick your authority,  and get your results. :)
Ok, well I’m confused, then. Consider:

Fact: Parasound offers something that changes the crossover point for the speaker design. They argue (and some here agree) that’s overall beneficial for sound because it reduces burden placed on speakers and amp while improving the integration of sub, speakers, and room.

Fact: PS Audio asserts they don’t offer that feature because it speaker crossover design shouldn’t be interfered with and that this adds circuitry that harms the overall sound.

Dilemma: either Parasound’s feature is beneficial to the achievement of audio quality *overall* sound or it’s not.

(a) If it IS helpful, then it IS ok to interfere with the crossover of the main speakers and PS Audio’s argument is wrong.

(b) If it IS NOT helpful, then it is NOT ok to add circuitry and interfere with the crossover of the main speakers and PS Audio’s argument is right.

If (a) is true, the PS Audio’s reasoning is specious.
If (b) is true, Parasound’s feature is detrimental to overall sound and shouldn’t have been included in their product.

There is another alternative:

(c) The question doesn’t really matter very much, and while people make design choices and then argue for them, these are tantamount to cosmetic differences and the differences highlighted are more marketing than engineering arguments. I’ve made a mountain out of a molehill. In which case, the answer would be (as I think was said by least one person above): "Fuggedaboutit."

I looked up your sub the Rel 328 and was wondering how do you connect it now? According to the manual you should use the speakon connector on the sub  and connect to your amps speaker binding posts in which case you wouldn't use the preamp crossover. It shows other ways of connecting but says this way is best for 2 channel system. PS Audio suggestion makes sense if you're not using a subwoofer but if you are a crossover is going to come into play somewhere and is not really something you see  a lot on 2 channel stereo preamps anymore it's  not a specious argument. The Parasound would give you the choice of using the subwoofer connected with the sub out and using the preamp to control the crossover and compare with the way Rel suggests but it doesn't look like it's a feature you really need but for some it could be useful as they wouldn't have to buy another component if they wanted to set crossovers so it is beneficial in certain cases. For example if I was using a small bookshelf speaker that only went down to 48hz without using a subwoofer  I would set the high pass on the Parasound say to 45hz making it easier on the amp and speaker since the speaker isn't going that low anyway you're not interfering with the speakers crossover. 
@djones I connect the Rel in the way indicated — Speakon to speaker terminals. It works well.
I have small bookshelves that only go down to 45hz. This is why I'm interested in this question.
And I believe I told PS Audio I had a sub and small bookshelves. That's why I'm confused about the validity of their answer.
Thanks for trying to think this through with me. The purchase of my amplification may hang on this question, other things being more or less equal.
Telling them you are using a sub and bookshelf speakers their answer makes sense they know the sub probably has a crossover, most all do so you don't really need it in the preamp. Manufacturers have different ways of looking at things PS Audio isn't  wrong and neither is Parasound it just depends on what your objective is one advantage of using the Parasound built in crossover is you can adjust it without having to get behind the subwoofer if you like to change it depending on the type of music or if you're watching a movie using it as a 2.1 system for HT. 
... I'm looking at Dynaudios and Salk WOW1's

Considering the diminutive size of the WOW1 (7 x 9 x 10.75 inches, including a 4.5 inch woofer) my guess is that **in this specific case** the sonic benefits of keeping the deep bass out of the speaker are likely to outweigh whatever sonic downsides may result from introduction of the P6's crossover circuitry into the signal path. And if that proves not to be the case the P6's crossover circuitry can of course be switched out of the signal path.

Without knowing the specific Dynaudio model(s) you may be considering I wouldn't want to speculate on the net result of that tradeoff .

Regarding the dilemma cited in one of your recent posts, every design approach has tradeoffs associated with it. And the net result of those tradeoffs usually depends on how well the specific design is implemented, and on how it synergizes with the rest of the system. So I would not consider the rationale of either company (PS Audio or Parasound) to be specious. And in choosing between the two products I would take into account the specifics of the application as much as possible.

Good luck. Regards,
-- Al
I love how some people here will answer questions by COMPLETELY disregarding the question and offer their own completely unrelated set of rules that pertain exactly ZERO to alleviate the op’s confusion. Funny thing is their advice is shockingly unhelpful and wrong. Really getting tired of these self proclaimed "experts" and unfortunately they seem to be the most active members on this forum. Their goal being not to help but to confuse and muddle. My only advice, is that you really have to do your own research outside of the realms of this forum because the people that answer first, are usually the ones that i have just mentioned and as I have said, they are not helpful for the most part and until they choose to go away this site is almost useless.
Thanks Doug for weighing in. I may write to Salk. I appreciate the various views, and may just have to remain agnostic because I cannot sort out what's best. I'll go listen and consider my day to day needs. 
@hilde45 & @lukaszwk  Agreed that people with an axe to grind hurt the forums... disagreed that this makes the place worthless.  I've learned so much here.  If you hang out enough you can get a sense of who to trust... and learn a lot in the process.  

As a shortcut judgment...  always believe @almarg .  And if you click on a username you can go look at their last X posts and see what you think about their recent contributions.  
I do enjoy reading certain individual’s posts, people with actual engineering decree and knowledge surpassing 99.99% of people here, like Atmasphere’s posts but people like that are few and far in between. This places has slowly been losing its luster and usefulness, for me at least. But to each his own. If you can truly be selective as to who you listen to, it can still be a useful place at times. But I think I’ve had it. At least for awhile.
@almarg and @douglas_schroeder and all,

I never complained about axes to grind; I am just trying to get straight. So, I emailed Jim Salk about this question, giving him all the information about my sub, which amps, etc. The short version of his answer is that crossovers for the main speakers can help. Here’s Jim (I hope it’s ok that I’m quoting him):

"I normally let me speakers run full range and bring the sub up under them. But, of course, I am always using much larger speakers. In the case of the WOW1’s, they are down 3db at 48Hz. So I would set the subwoofer crossover to 55 or 60Hz if you wanted to play them full range.

But there is a case that can be made to use a preamp/processor to set the crossover higher. For example, most home theater processors would probably define the WOW1’s as being a “small” speaker and use 80Hz as the crossover point, running the sub with no crossover (all pass) since the processor will only send audio under 80Hz to the sub. The benefit of this is increased power handling. The deeper a speaker plays, the more cone movement is required. The cone can only move so far (XMAX) before it bottoms out. But when eliminating some of the bass duties, not as much cone movement is required so it can play louder without bottoming out.

Of the two, I would probably opt for the latter approach since it would allow your system to play louder without bottoming out the WOW1 woofers."

@cal3713 Thank you kindly for the nice words.  I always value and enjoy your posts as well.

@hilde45, Excellent answer by Mr. Salk, as Doug had prognosticated.  I would add that even if a woofer does not bottom out, as it approaches that condition the sonics of a speaker are likely to be adversely affected in various ways.  And that figures to be especially true in the case of the WOW1, given that its woofer is undoubtedly handling just about the entire midrange, as well as the bass.  (The woofer it uses has a recommended frequency range of 60 Hz to 3500 Hz; the tweeter it uses has a recommended frequency range of 2.5 kHz to 25 kHz).  

Also, if you were to go with a different speaker now or in the future, as I mentioned earlier the P6 would provide you with the flexibility of being able to conveniently remove its high pass filter from the signal path, via the switch it provides on its rear panel for that purpose.  

Good luck.  Regards,

@almarg Thanks for that information. At this point, choosing will come down to listening and then seeing if the Parasound is good enough so that that extra feature tips the scales towards it.

If I didn’t prefer the Parasound, though, I supposed I could get an external crossover and have that feature with a different preamp — perhaps with more precision, even? That would allow me to get the preamp I like best *and* having the control a crossover gives.

If I have this wrong, or if adding a crossover is a complicated affair, please set me straight. This solution could be the one that splits the difference.s

I learned something here, but not quite enough to make a judgment about Parasound's approach.
No amount of tech discussion or specifications analysis resolves such questions.  Listening comparison is the final arbiter  especially since preferences vary so much between hobbyists. 
Be aware that if you ever wish to upgrade and sell speakers  anything unusual or customization taking it away from stock and requiring specific components would likely devastate the resale.

This may sound tough, but trying to be helpful; At your level along the performance spectrum the difference between your. Choices is rather small. It is one of dozens of potential upgrades and improvements in the field of domestic audio. Your selection will have only a smaller nudge toward upper end sound. It takes many such incremental,  or fewer huge moves to get very high end results. To attain far more significant changes you will need to move up the speaker food chain, I. E. Larger floor standing speakers:  in my experience bookshelf and sub is not as capable as large floor standing speakers.  :)
@douglas_schroeder Thanks for the reality check. I realize I'm just playing with tinker-toys, so to speak. This research can really get away from one — there are so many suggestions I've gotten which has essentially dangled the carrot of the higher level gear before me. But I am trying to remain located within the parameters which are realistic for *this* enterprise: bookshelf speakers, sub, $3k budget, smaller room. 

I may realize after listening that given the small differences possible, some features which might make higher end folks cringe will actually be practical and convenient (e.g. a knob, a remote, etc.), and I can accept them as level-appropriate. 

By the way, I wasn't considering making any modifications to the speaker itself — just getting a box of some kind to interpose as a crossover control.

If at some point I gain a space in my house for larger speakers, your advice about that will be quite salient. (Just have to work on my WAF.)

If I didn’t prefer the Parasound, though, I supposed I could get an external crossover and have that feature with a different preamp — perhaps with more precision, even? That would allow me to get the preamp I like best *and* having the control a crossover gives.

If I have this wrong, or if adding a crossover is a complicated affair, please set me straight. This solution could be the one that splits the difference.

That’s certainly possible, of course. But the initial complication would be choosing an external crossover that would have minimal sonic side-effects while costing an amount that is reasonable in relation to the costs of the other components.

Some pro-oriented active crossovers can be had for less than $200, while other pro-oriented as well as audiophile-oriented models can cost many thousands. (The pro-oriented ones, btw, often provide only XLR and/or 1/4 inch connectors, rather than RCA connectors). I can’t comment on where within that wide price spectrum the sweet spot might be for your purposes.

Another possibility would be a passive crossover, perhaps constructed by yourself, consisting simply of a capacitor for each channel, an enclosure, and appropriate connectors. The value of the capacitor (i.e., the number of uF, or microFarads) would be chosen to provide the desired crossover frequency based on the input impedance of the particular amp that is being used. The main upside of that approach is of course low cost. The downsides include slow rolloff (6 db/octave), and the difficulty of determining what crossover frequency is optimal for the particular speaker and hence what the value of the capacitor should be.

-- Al

Thanks Al, I appreciate it.

To the OP, I'd also just like to note that Douglas is very right... given that your sub already has a crossover, you are completely fine without one. The Salk will play just like it was intended/designed without removing low frequencies and the sub crossover will allow you to integrate the two just as the sub was intended/designed to be used.

Again, as Douglas started, perhaps you'll be able to squeeze out a tiny bit more performance with a crossover, but honestly, I wouldn't worry about it at this stage. It might be fun to play with, or the process might drive you insane, but until you're thinking about pulling crossover components or building your own speakers, this is almost entirely academic.  I do still think (hope) the discussion is valuable and educational for you and future readers learning about these issues themselves...
@almarg @cal3713 @douglas_schroeder Q.E.D. as they say in logic. This clinches it for me. I do not want to start building crossovers, nor pay for expensive ones. I like the idea of keeping things simple. So, what I know now is this: the feature on the Parasound is not a gimmick, nor is it a necessity. It is a plus if and only if *literally* everything else for my ears is equal. I'm very happy with that answer and with the evidence for it. Thank you!