Are the performance of separates worth the price?

I am considering the purchase of an integrated amp or combination pre-amp/amp from the same manufacturer - both are based on similar technology.

The separates will cost approximately 45% more. Can I expect the performance to justify the price?
Absolutely not, if you consider that to do this right you would be adding the price of a good set of interconnects, two audio grade power cords vs one, rack space & footers, plus separate noise filtration for each separate component. It's simple mathematics.
It's like everything in life. While one may work perfectly fine, two are better. On the other hand, in audio, it may not be true. It depends on WHAT ONE or WHAT TWO you are considering purchasing. Obviously one Mark Levinson will be better than two Rotels. What will you be hooking them up to? $300.00 bookshelf speakers or $12000.00 floor standers? What is your aim? Ultimate fidelity in the ultimate system or less? I think you should buy what you can afford and then a little bit more. The only mistakes I have made in this hobby occurred when I got cheap and did not get what I wanted.
Please give us some more info. on the specific components involved. You really need to compare model by model w/in a given Mfg's line-up. And knowing the rest of your system would be very helpful also. Also your budget, your tolerance for complexity, possible WAF, etc. (IMO, your question is so theoretical it's very hard to answer).

I saw from your previous threads you were considering purchase of the BAT integrated. Is that still the case?

With separates you have flexibility. With an integrated, if you want to change anything, in many cases you have to sell it & start over. I've never heard really expensive integrateds like the BAT, or the Rowland, but if it were me, in that price range, I'd go for separates.

But, if you are new to the hobby perhaps, or if there were another factor like someone else using the system who didn't understand turning on or off many components, an integrated could make lots of sense, esp. to save $$. (I'm not inferring that an integrated is only for newbies--I've owned them & I know there are some that I'd drool over in certain applications). Just my 2 cents! Good luck.
If someone answers your question in the abstract, you'll probably get a different answer than one that is specific to your budget and listening objectives.

As several have already suggested, we need more info from you to be able to provide a good answer. There are some really excellent integrateds on the market today, but the better ones are not cheap -- the best ones start at around $3000, and run up to around $6000 (for example, the Musical Fidelity Tri-Vista, which is one of the best and most powerful integrateds, retails for $6k).

First and foremost, what is your budget? If you have a modest budget -- say, $1500-2000 -- you may well get better performance from an integrated (such as the Creek 5350SE) than from a preamp and power amp with the same combined price tag.

Second, how much power do you think you will need? This is an indirect way of also asking: how big is your listening room; how efficient are your speakers; and what are your listening tastes (listening to symphonic music, or rock at high volumes, places very different demands on the amp than listening to chamber music).

Third, what kind of speakers will you be using? Some speakers perform just fine with amps that provide moderate current, while others really need a high-current amp to "sing".

Last, what are your future plans for your system? If you intend to continue upgrading in the relatively near future, you might be better advised to save some more money and make the jump directly to separate components (not the same as making the jump to hyperspace...).

If you can respond to these questions, I think our "gurus" can give you a better answer.
I just love these posts(no offense)!..."what's better, a tube amp or SS amp?"..."what's better, bookshelve speakers or floorstanders?"..."What's the best speaker for acoustic guitar?"..."What's the best car for driving to work!?"
This stuff cracks me up!
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Additional info:

I am considering the soon to be released Jeff Rowland Concerto Integrated vs. Concerto Pre-Amp and Model 201 Monoblocks (or) the BAT VK-300x Integrated vs. BAT VK-31se and the BAT VK-250.
More additional information:

My speakers are Vienna Acoustics - Beethovens
Space is not an issue, expect to keep for a few years, willing to pay the additional price for separates if it is worth it.

If you have the cash, go for the separate components. I don't know which would be better for you speakers and I've not heard either brand of electronics, but if it is ultiamte performance and flexiblility you want, than separates are the way to go.
Good listening,
If you are going to only have one source, (CD) then I would skip the preamp, get the best amp you can afford and go for a CD player that offers volume control such as the Audio Aero Capitole Mk 2, Wadia, Levinson or Accuphase. You will get a top notch source and a preamp in one package. Some of these units offer digital inputs, so you could run a DVD player into them for HT. You save a set of interconnect, power cord, isolation and shelf space. I love a great preamp, and consider it to be one of the most important links, but if you have a budget and don't need a lot of switching ability it's tough to beat the CD player direct for bang for the buck.
You may want to contact Sumiko and ask them what the like.
A warm amp. would not be a good idea.

My thoughts are that integrated amps and one box cd players tend to represent far better "value" for the money. The cost savings of one chassis (vs. two or more) for the manufacturer are siginificant and passed on to the consumer for the most part (while we don't want to admit it, a fair amount of the retail price on any high end audio component goes to the fit and finish of the chassis, with some exceptions...lamm comes to mind). Second, the elimination of external connectors with hard wired connections also tends to produce sonic benefits. That said, at the (very) top end, separate chassis do have the edge because of the ability to separate the power supplies from the rest of the components, as well eliminating intra-chassis resonances and the like. While few will disagree that separates provide the best sound, integrateds will provide more value. Of course this is my opinion and like all generalizations will not hold to be true all the time.
Ejlif is correct in suggesting a Cd player with volumn control. Unless, of course you need the pre for vinyl. The only problem with most such Cd players is that they don't have an analog passthru for your tuner.

I am only aware of one Cd player that has recently incorporated the anagog passthre and that is the Audio Aero Mark II. You can get an older AA upgraded with a new circuit board and it will also handle analog.
there are some pretty good separates and some pretty good integrateds. I think your own ears will lead you the way that it is best for you.

My ears led me toward separates, but these things sure take up quite a bit of room!
Depending how much are you willing to spend. If over $2K, i would look into used separates. Better value, better sound.
The answer is yes. However, you really did not state enough in your question. Is the amplifier section of the intergrated equavalent to the stand alone amplifier. Check the manufacture's specs. If things like damping factor, power output, slew rate, signal to noise ratio, IM distortion, etc, are similar, then the units will probably preform about the same. Inaddition, if these units are from a quality manufacturer, and well constructed, then the likelyhood that the intergrated amp will offer any comprises in sound quality is low. Most of this is psycological anyway. You probably have always been told that a really high end system has to be separate components. What you have'nt been told is that many 'really' high end systems can sound like poop too. There was another good bit of advise offered here too. If you plan on using only one source, then skip the preamp all together and plug directly in to the amp. You can accomplish this with either an amp that has front panal volume many high end manufactures are still doing this....or a source that has variable outputs, etc. Furthur, if you are going to use more that one source, but no phono, or tape or recordable CD, etc, you can still do this with a high quality switchable multiple aux input device. If you want to record, you could also plug directly into the recorder (cd, dat, tape, ect).