Affordable Processor with Fabulous 2 Channel ?

@auxinput

The SSP 800 stereo performance or when used as a stereo analog preamp is superb especially coming from an AV pre pro but the Sigma SSP is slightly better but not by much. The difference was subtle. They sounded similar but the Sigma SSP has lower noise floor thus quieter, better image focus, everything were rendered more faithfully, slightly better dynamic range, etc. But again the difference was subtle.

The Sigma SSP’s USB DAC input signal path circuit architecture, spdif & Toslink input stages as well as analog input stages for only front LR channels were copied and pasted from that of the Classe CP-800 stereo preamp/DAC. The analog input stages of the CP-800 stereo preamp is known to be superior to that of the SSP 800 pre pro and sounded better than the SSP 800. Actually the stereo performance of the Sigma SSP is very close to that of the CP 800 stereo preamp, regardless of whether using the XLR stereo analog inputs or USB DAC inputs.
It takes highly trained ears in order to tell the difference between the two.

Both Classe CP 800 stereo preamp/DAC and Classe Sigma SSP’s front channels use exact same DAC chips but the CP 800 uses 2 DAC chips per channel whereas the Sigma SSP uses only one DAC chip per channel for its front LCR channels. Both the CP 800 stereo preamp/DAC and the Sigma SSP USB DAC input port sounded significantly better than their other digital audio inputs (spdif, Toslink). These two preamps were designed around the USB DAC input ports. You can read more on that online under Classe CP 800 reviews. However the Classe CP 800 stereo preamp/DAC originally retailed for $1k more than the Sigma SSP pre pro which makes the Sigma SSP a better value.

However, when designing a cheaper AV pre pro (Sigma SSP) Classe had to make some sacrifices such as limited features, limited connections (inputs & outputs) on the Sigma SSP in order to build a cheaper AV pre pro than the SSP 800 without sacrificing audio performances. There are features and connectivities that are omitted when designing and building the Sigma SSP.
You won’t find legacy analog video connections, no multi-channel analog audio 7.1 inputs on the Sigma SSP.
Classe also decided to limit the XLR balanced audio outputs only for front LR channels only (they are true differential or fully balanced circuitry) and the rest of the channels are single-ended design and have only RCA outs.

The Classe SSP 800 and Sigma SSP have different design philosophy. The Sigma SSP is optimized for stereo listening to music and is for someone who’s looking for an AV pre pro but main priority will be for two-channel listening to music but wants to have good multi-channel capabilities as well for HT or movies.
The Classe Sigma SSP isn’t for someone who’s looking for a processor for strictly HT use, that would be more for the SSP 800 or Datasat, Trinnov, Anthem, Marantz, Lyngdorf MP-50, Audio Control Maestro.

Actually the new Anthem AVM60 pre pro ($3k retail price brand new) performs extraordinary in surrounds for strictly HT use with the ARC2 engaged. The ARC2 (Anthem Room Correction) is a phenomenal room correction and is one of top notch and is probably on par with Room Perfect & Dirac Live. The Anthem AVM60, with the ARC2 engaged, will outperform the Classe Sigma SSP when used for surrounds or HT and rivals the much more expensive SSP 800.
But when used as a stereo preamp with room correction turned off both Classe Sigma SSP & SSP 800 sounded better than the Anthem AVM60. Hands down.
It all depends on what you are going to use the pre pro for.

The Anthem AVM60 pre pro is an absolute steal and if you are going to use it for strictly HT or surround movies the Anthem AVM60 will be perfect. But the ARC (Anthem Room Correction) is somewhat difficult to implement and get it set up properly. It isn’t plug n play kinda thing like the Audyssey in Marantz & Denon products.
But if you know how to set it up correctly it is very effective and extraordinary, way better than Audyssey.

However, the Anthem AVM60, both Classe SSP 800 & Sigma SSP, the Bryston SP3 aren’t equipped with video processor / upscaler. The video is simply pass through unaltered. They simply switch the video, they don’t process it. It makes more sense not to equip av pre pro or AVR with a video processor / upscaler. IMO the video part is better off handled on your display or an external video processor or the Oppo players are very good in this area.

Agree on all points regarding the SSP800. It’s a hi-end preamp with stereo bypass which I’m using when listening to my Aurender A10 server because I find the dacs on the A10 a bit better, but the classe’s own are fantastic and can’t be beat with the prices they are going for now, which is around $2500. I also had the Krell S1500 for a year before the Classe, and while it was great for HT, 2 ch just didn’t do it for me. Not really close TBH. It’s GUI was also very clunky.
I’m most likely gonna update to the Lyngdorf M50, room correction and Atmos, but I’m no hurry for now.
Too bad the Sigma doesn’t do Atmos, cause the Lyngdorf is 2x the price.

@btw22 

+1. Actually the GUI on the Classe SSP 800 is not any better. 
The new Sigma SSP Mk2 does Atmos & DTS-X, 4K video pass through but not HDR compatible and the new retail price now is $6k. 
The Lyngdorf MP-50 is better IMO especially for HT. I've heard that its stereo performance is very good too. I think the Lyngdorf MP-50 retails for $10k. 

@soix 

Yes I totally agree with your points. Having a good quality dedicated stereo preamp and a cheap AVR or a cheap pre pro will make more sense since the HT formats keeps on changing constantly. But not everyone would want two separate units : one stereo pre and another pre pro or AVR in their rigs maybe partly due to limited rack space or other reasons. Some would also want very good surround sound quality as well for their HT needs as well as stereo needs. Cause cheap AVR and pre pro would not sound good for HT (movies). Having the best of both worlds will cost a fortunate indeed. Having both high end expensive AV pre pro and high end stereo preamp can be very costly. And some people do not care about the latest formats and would only like conventional 5.1 or 5.2 setups. That seems to be the case with the OP (erik_squires). He does not need the latest AV formats eg Dolby Atmos, DTS-X or 4K video pass through. Our varying needs would dictate what to get. 

I'm very well aware that AV formats become obsolete pretty quick. 
And high end stereo preamps would of course sound better than high end AV pre pros in stereo. No doubt. 

I happen to have two separate setups in two different rooms : a stereo setup in my dedicated stereo listening room, and a dedicated HT room in a separate dedicated HT room. But not everyone have what I have. 

@erik_squires 

The Bryston SP3 lacks support of the latest most current formats such as Dolby Atmos, DTS-X, Auro 3D, 4K video pass through, etc. that's why its resale value plummets in an after market. 
The same with the Classe SSP 800. That's the main problem or drawbacks with AV pre pros or AVR that lack supports of the latest most current AV formats, their resale values will plummet quite drastically. As mentioned above that AV formats are constantly changing, evolving, etc.
Welcome to the ever changing AV world.