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SS Amps for C4 Signature II's

OK, I’m curious about amps.

I have a set of C4 Signature II's that are running with ODYSSEY KISMETS and seem to sound pretty darn good. But, they aren't the be all to end all amps, and they never were meant to be. A good sounding "value", well yes. I have no major complaints on their sound for the price. So, lets not pick on them but look at what might be an upgrade for these speakers. Dragging amps home to audition is a physical exercise in and of itself with 75 pound and heavier weights I'm seeing!

I have just a few amps that seem to be very compelling for different reasons and I’d like some viewpoints from all of you that have been here, done that, and especially C4 users. C4’s can be an odd load at the low-end.

1.0 The first thing is CLASS A verses A/B. The image stability of CLASS A amps is derived from the voltage rails being sag proof (or more so) than class A/B since the are charged up all the time. Yep, that eats power, too. Still, this is an advantage if you pick the right amp.
2.0 A/B amps come in two flavors, high bias amps like an old McCormack DNA-225 (it gets plenty hot when running!) or a lower bias unit like my ODYSSEY KISMETS that refuse to even get warm. The “hybrid” high bias amps that are around (PASS LABS as an example) can run CLASS A pretty high (up to 40 watts in the case of a X350.5). Is that enough to capture the CLASS A “flavor” and A/B efficiency?
3.0 Weight. Man, how do you move your stuff? Some amps are frighteningly heavy making a dual MONO set-up seem logical, but even more expensive. I may get the sound, but the weight can drag you down. Yes, weight is part of the deal in a good power supply, which means get the power you need.
4.0 I HAVE to be able to listen to them before I buy. I don’t need “more” of the amp I have now, worse or the same general sound, but better. So in-house audition is a must. I can’t easily get the PASS or ANTHEM products making auditions and service a pain. But, if it’s worth it, I can try. I can get BOULDER products but they are WAY high priced.
5.0 I am using a PASS LABS XP-10 pre amplifier so I have full balanced or RCA outs.
6.0 Is it just me, or are the specs on these units hard to come by? VA transformer ratings, CAP values in the power supply ETC? Not that this is all there is, but it helps.

So considering those points, and if I’m seeing all this right, we can sort of claw through some of this on paper.

My first choice, again, on paper; Plinius SA-103.
I have heard the Plinius on Theil CS2.7’s, and it imaged VERY well. Can’t comment on the musical balance on my speakers, though.
All CLASS A capability but can run A/B with the flick of a switch so I can listen to the radio with A/B!
Seems to be a solid design with good sonic ratings.
Plenty of power (125 watts / 220 watts) for the volumes I listen to (83 dB SPL average where I sit 15 feet away).
I can get another one if needed for silly amounts of power.
Seems to be nice at low impedance and high current situations.
Wow, it gets warm in CLASS A so keep the music going!
Good paper specs on S/N and separation.
I can actually pick this amp up at 85 pounds.
Price is “reasonable” for a high-end amp.

My second choice is a PASS LABS X350.5 as I’m told that the sweet spot for PASS A/B sound is this amplifier. PASS pure class A is too expensive.
40 watts of class A capability may capture the sound I need?
Seems to be a solid design and also with good sonic ratings.
WAY more power than I’ll ever use, though.
Never need to buy another amp for power.
Stable into low impedance.
I CAN NOT safely pick this amp up at 135 pounds!
Price is “reasonable” if you can find a used one for a high-end amp.

My third choice is an ANTHEM P2 that some say is a giant killer (I don’t see any dead giants laying around anywhere, though).
Seems to be a more standard A/B amp for home theater but…I keep being told to listen to it.
Seems to be a solid design (full of protection circuits).
WAY more power than I’ll ever use, though.
Never need to buy another amp for power.
Stable into low impedance to an extreme.
I can pick this amp up at 75 pounds.
Power rating and light weight make me wonder about the current delivery capability.
Price is “reasonable” for a high-end amp.

My fourth choice is a BOULDER 860.
Doesn’t seem to “double-up” on power into 4-ohms.
Can’t be run “mono” to add one later on.
Built well.
Paper specs are impressive (S/N and separation) but gets a knock for harshness in the midrange.
Seems awful light at 45 pounds to provide a big current reserve in the power supply.
Price seems high for the lightweight power supply.
rower30
p59teitel
312 posts
 
"I've switched around preamps and the tube units I've tried left me wanting...for detail and microdynamics. I just can't forget all the nuances of the music I hear with SS units that simple vanished with tube pre amps. Yep, the tube "harmonics" and tonal balance is there, but you loose the qickness and finer detail. My ear seems to want to hear all this. When I have a tube unit in my system, and switch it out, I don't want to go BACK to the the tube unit."

Like you I am running detailed speakers (Revel Salon 2s) and have the same need for speed. I'm currently using a Symphonic Line tube preamp and at least with this preamp I have microdynamics and detail in spades. Very fast too - not getting the slowness and rounding off that it sounds like you're hearing with the tube pres you've checked out.

Your Plinius SA-103 choice seems a sound one albeit with one minor caveat. I ran a Plinius SB-301 in my system before it was replaced by the Symphonic Line Kraft 250 monos three months ago, and it is a very good amplifier. The Plinius provided plenty of dynamics and slam in spades, and had no problems driving low impedance loads. It is a bass monster!

Plinius microdynamics are quite good too, although the SB-301 is not in the same league as the SL monos in that regard (which list for 3X as much and should be better). I also understand that Plinius and Dynaudio are a very popular tandem in Europe, so it would seem there's some synergy there. Very good soundstage with the Plinius too. The one caveat is the Plinius house sound is just a wee bit rolled off.

Getting back briefly to the tube preamp discussion, the Plinius SB-301 sounded really really good with the SL tube preamp, which was a big step up from the Plinius M8 SS preamp. I probably would have stayed with this pairing for quite a while had the Kraft 250s not become available at an insanely good price.

And finally, speaking of Symphonic Line - that's another possibility for your C4s.
rower30 OP
211 posts
 
Funny, the KISMET's are and ODYSSEY knock-off of the SYMPHONIC line! They aren't so bad at all, by the way.

I auditioned power amps today with a pair of DynAudio C-1 speakers as they are close to the C4 in general timber (those are GREAT small speakers!). WOW, was I surprised.

I listened to a top of the line type tube integrated amp. Very nice soundstage and texture, but...it was still blending the images together like a faint airbrush. I HATE that effect. I'd tell you the brand, but it didn't matter, really, as I moved on in a hurry. Tubes just aren't working for me yet.

The next jump was an odd French made chrome finish integrated CLASS A audio stage with CLASS D power supply hybrid integrated that I called the waffle iron. Now THAT unit sounded good at $15,000.00. But, it was a full system, though; DAC, amp, pre, power, the works.

After that we listened to the PLINIUS SA-103. Rats, this unit sounded too warm (sound, that is but it did get physically HOT) and also not rich and detailed enough. Sounded like a tube unit to me. So my great idea died right there. It fell far from my expectations. So much for paper spec shopping.

Then we tried a BOULDER 860. This amp shot right to the are I like to hear, crisp, detailed, rich and full of inner microdynamic detail and a big expansive background. MUCH better than the SA-103, by far, for my ears.

Then we went to a SIM Audio MOON Evolution 150 watt/channel integrated that was similar to the 860A. Hey, now THIS thing is rocking! It had what the BOULDER 860 had but with even better midrange texture (what tubes seem to do well) and a HUGE soundstage as things opened up. It was remarkably good. The richness was intoxicating.Everything was in its place, and a place for everything.

So now, I'll drag my somewhat light 50 pounds each KISMETS down to the stereo store and A to B to the 860A and see what kind of jump in sound I hear. And, I'd like to drag the Boulder 1060 into the mix. too.

I had NO idea how good the SIM AUDIO stuff was. And, it idles at 55 watts, 5 watts less than my two KISMETS. I can afford to run these 24/7.

The BIG issue is now is a new 860A at $14K or a used BOULDER 1060 at just under that. At the volume I listen to, the 860A had more impactful bass and dynamics than the Boulder 860. But, would the 1060 close the gap and give more headroom? All the Boulder amps are Eco to the max at idle, 17 watts! So, I want to go with SOUND verses what I paid relative to any list price. The 1060 has to be BETTER at 80-83dB average SPL volumes than the 860A. A deal relative to price and worse audio isn't a deal to me. I'd rather pay 14K for the MOON 860A than 12K for a Boulder 1060 if the 1060 sounds worse (who cares what it "listed" for) where and how I use it. "louder" isn't my objective.

This never gets easier, or cheaper! So I save like a demon and maybe this spring I might be ready. My budget just went up time 1.5!
zd542
5,339 posts
 
"OK, but there STILL has to be a passive X-over inside the speaker after you remove jumpers to allow vertical bi-amping as you can't, or don't want to, run full range into the mid/tweeter (assuming a three way speaker) and woofer. The set-up makes sens when you remove passive cross-over components."

After reading this response, I don't think I did a very good job of explaining Vert Biamping. Of course there is a passive xover in the speaker. You couldn't do a vert biamp without it. The idea is to work the 2 amps exactly the same way so the sound is consistent. Each amp powers the whole speaker. It amplifies the highs and lows thereby putting the same load on each amp.

Also, you say that the setup makes sense when you remove the passive xover components. That's not correct. You have to have the xover in the speaker or it won't work. If you removed the xover you would just be sending the full frequency range to each driver. That's why you need stereo amps for it to work.

Sorry if I didn't do a good job explaining in my first post.
extravaganza
373 posts
 
but have in mind that you have C4 not C1,for that reason sim audio integrated may not provide enough power for c4
rower30 OP
211 posts
 
I'd go to the 200-Watt into 8-ohms MOON 860A model with the C4's, or the Boulder 1060 if it sounds better. I don't really need more power at the expense of sound quality.

The tube unit was made by Octave. It was the best I've heard so far, but the better SS stuff held my ears attention to a higher degree.

Like pre-amps, amplifiers are vastly different in sound. From thirty years ago, the differences have gotten larger.
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