How important is the pre-amp?

Dare I ask if it is possible to get decent sound from a home theater preamp?

Not even. The problem is HT means surround means processors means noise.

Think of it this way. Some of the very best preamps out there are designed to power off the display when listening to music, because of the detrimental effect of even that tiny little bit of extra stuff running. Seriously. Stop and think about that. People can actually hear the sound degradation caused by something as seemingly minor as a function display.

Now imagine a whole big surround processor chip, about the size and power of the one in your computer. The noise and distortion that thing is generating, makes my skin crawl just to think of it. But then that is maybe partly because I know from experience, from having actually tried and compared these things. It is abysmal what they can get away with having a big screen to distract from the reality of the sonic dreck coming out of one of these things.

@smandlej 

I just ordered the Allegri Reference preamp myself. So I'll soon know the answer to the OP's question.

My Classe SSP-800 processor/DAC has been my systems preamp since 2009. It has served me very well but I've read enough from millercarbon and others to have learned that my
2 channel isn't at its best with the Classe(as great of a unit it is). My surround and digital will pass through the Allegri(until I buy an external DAC) as well to my front speakers. I don't think it will change anything sonically though. 

John at Townshend told me that "there is no need at all" for additional Allegri isolation.
"Save your money" he said. 

IMHO,
The preamplifier is extremely important.
I would consider it right up there with your choice of speakers.
That being said,
The improvements tend to be incremental, relative to price.
Trust your ears and buy the best you can afford. With consideration towards future system additions.

ing@azwineguy

Dare I ask if it is possible to get decent sound from a home theater preamp?

sound quality is a combination of a number of things.

on this forum with it’s 2 channel focus signal path’s need to be as pure as possible (including the most pure preamp) to optimize the 2 channel media. along with rooms and acoustics which promote 2 channel listening, which is mostly diffusion. the subtle nuance is critical. the speakers are intended to work ’with’ the room.

but a dsp based multi-channel Home Theater system has a different set of rules. the room needs lots of absorption since with 11 to 15 surround speakers for performance you want direct sound not reflected sound. the challenge is still low noise but the dsp process and adding all those speakers makes it less critical (the concept of noise.....is actually signal to noise); especially if you play at the top of the dsp food-chain with 15 speakers and a Trinnov Altitude 16 or 32 processor (it's damn quiet).

https://www.trinnov.com/en/products/altitude16/

but rooms are not chameleons; you have to choose......and if you combine 2 channel and serious multi-channel then one (or likely both) will be compromised. i’m talking degrees of good here, not saying both cannot still be enjoyable.....but still they both can’t be truly optimal since the room rules are different.

i have 2 separate serious rooms; one for 2 channel with mostly diffusion for the walls and one for dsp multi-channel/movies.....with 15 speakers and 3 subwoofers.....and lots of absorption.

you can get fantastic sound from a Home Theater processor, but it’s lots of effort. and if you get fantastic multi-channel sound, then playing 2 channel media will be compromised......although it’s possible you might like some sort of multi-channel effect more than just using 2 speakers for the 2 channel media from that Home Theater processor.

A few comments on the "transformers are the answer" topic.  I agree that especially when you have an impedance mismatch, particularly the wrong way (high into low), that needs **transformation** rather than gain or attenuation (fractional gain),a transformer could be very good.

Its that "could be" part.  They have many issues - several notes above, several not. And like most problems, they can be mostly solved with money, lots of money, and few have attempted it.   No market maybe, or very very hard.   An ideal, variable, volume-controlling transformer must be VERY expensive.

Ditto resistors.  They have issues.  You can buy better ones.  But.... I actually think even modestly good (name brand 1% metal film) resistors are pretty transparent. And with resistors there is a mature market for VERY good ones, and while they too are expensive (like 10-50X the cost of modestly good ones), even at 10-50X they are still less than half a buck (Caddock, DALE mil-spec noise controlled, non-inductively wound, blah blah) or were the last i checked which i admit was years ago.  To be clear, you need a dozen to hundreds of pairs depending on how you implement the solution.  I use 11 pair.  Oh, and a micro-controller  to control the mess.


But look a the big picture: we are now worrying about two more resistors in the signal path, one series one shunt. There are likely dozens in your signal path already. Are you replacing all of those too? Or removing them and inserting.... what?

I firmly believe that for 99% of applications, a true, discrete, stepped attenuator using a minimal number of resistors, great contacts, and good (not awesome) resistors is pretty darn transparent. I can say for sure its revelatory compared to what nearly all of us have heard - and I can do A-B-C side by side tests since i have them all, independent of the preamp circuitry, with a switch to do the rest evaluations.