But high end pre pros like the Classe SSP 800, Classe Sigma SSP, Bryston SP3, Meridian Ref 861 v8 are great for both stereo and surrounds (HT) and can function as high end stereo preamps.
I was going to recommend the Bryston SP3 to the OP (Eric_Squires) but the SP3 is expensive ($9500 retail price) and is a current model, so even if you could find a used one it would be still pricey. The Bryston SP3’s stereo performance is even better than both Classe (SSP 800 & Sigma SSP) pre pros.
The Meridian Ref 861 v8 pre pro is even way more expensive around $32k brand new, But its stereo performance is spectacular.
Expensive processors such as Datasat and Trinnov are phenomenal for HT but I don’t think they put priority on stereo performances. Today Datasat & Trinnov are probably the best HT processors you can get for strictly HT use.
Both the Classe SSP 800 & Sigma SSP stereo performances for stereo music playbacks are on par with high end stereo preamps that are in the $5k range IMO. Their stereo performances aren’t compromised at all like those lower end pre pros from Marantz, Denon, Yamaha, Onkyo/Integra, Anthem.
Actually the Classe Sigma SSP is optimized for stereo listening.
People who bought the Sigma SSP put priority on stereo performance for music playbacks.
Unless if you plan on getting expensive stereo preamps that cost upwards of $7k and up, then yes they would most likely be better than stereo performances of the Classe Sigma SSP or the SSP 800. No doubt.