Are the performance of separates worth the price?

My favorite way to get the separate amp performance without the preamp cost, and to avoid the somewhat less stellar performance of an integrated amp, is to use EVS Ultimate Attenuators, from tweakaudio.com.
If playing only one source, such as CD's, you can usually do without the preamp, and still use a CDP lacking built-in volume control, if you go with the Ultimate Attenuators.
They plug directly into the RCA input jacks on your amp. There is a model for tube, or transistor amp matching.
The list price is $350, which is often less than the cost of the interconnects you no longer need when a separate preamp is absent.
The stepped volume controls are not as flexible as continuous ones, but the quality of a fine amp can be revealed, as never before.

the integrateds get rid of the cost and sonic influence of interconnects so there is a big gain there. The integrates do tend to be on the low end of the power spectrum and tend to not be high current amps from what i've experienced. that can present issues with hard to drive speakers

I would have to agree with the above post, especially concerning the Jeff Rowland integrated amp. I have heard it, and it comes very, very close to the performance of the JR separates. However, if you have one source such as a CD player that can play through an amp directly, I feel that you may be better off going in that direction instead. Good luck with your purchase!

I think you'll find the law of diminishing returns are in order. You may pay 45% more, but you won't get a 45% improvement in sound. It gets very expensive trying to chase that last 5% or so of sonic nirvana. Is it worth it? That all depends on who you ask.
If you're set on staying with the same manufacturer of preamp and amp, I'd recommend to just go ahead and get the integrated. The Beethovens are a relatively easy load, so it's not like you have to have a beast of an amp.

Cheers,
John