Best Of

I would say none of the above and instead look for a Pioneer Elite SC** home theater receiver. Run in stereo it will power the CRS with no issues and you wouldn't have to get audio separates or an underpowered integrated amp until you could afford to do things right.

Plenty to look at on Ebay in your price range.

Also, don't rule out a brand new combo of something like a Wiim pro (as a streamer and preamplifier) and a cheap mono block pair of amplifiers. This cold be a temporary system while you save for an upgrade.

Stick around and keep an eye out on this forum as well. Many deals been had here over the years!

Enjoy

1. Carver M-500t Power Amplifier - 250 WPC, Tube Sound 450.00. IIRC Most if not all of these inverted the signal, IF so they ARE NOT SDA compatible.

With your SDA's you need to keep to a COMMON GROUND amp, some of these here are not
GFA-5400 power amplifier do not believe it is common ground.
Most if not all of these are old enough that you're taking a big gamble that it won't soil the sheets. When some of them DO soil the sheets they can and will take other gear with them, like speakers.

I would also recommend an integrated amplifier on that budget.

Enjoy!

I would also open up your search to Integrated Amps if you haven't been looking at those. If you don't already have a preamp, an integrated might be an easier solution. Separate Pre-amps have their benefits, but some of the well designed integrated amps can provide a very satisfying solution for less money and less potential headaches. NAD, Musical Fidelity, Cambridge, and even Yamaha make some good integrated amps.
For NAD, the C365BEE or C370 might be worth looking for. For Musical Fidelity, it might be hard to find something under $500, but you might get lucky. Just beware that any amp that is 20+ years old might need some refreshing. Amps that sound good usually run hot and heat over time wears out some of the components. Most of those Adcom amps you mentioned are closer to 30+ years old.

Going from two higher end DS DAC's to a mid-line dedicated R2R DAC for me was no contest. The R2R smoked both of the DS DACS's and the two, compared in the same system with no other change, wasn't even a fair comparison in my book. It was akin to having a race between a Yugo and a Bugatti.

I now utilize 2 R2R DAC's in the rig and will never own another DS DAC again. Just my 2 cents on the subject.

The first word that came out of my mouth when I first heard the R2R DAC was a very enthusiastic, "WOW".

FWIW.

Tom

Some Delta Sigma dacs don't even use chips, some use FPGA, one small manufacturer is even using 8 dual triodes and a BFT to do upsampling and filtering.