Peachtree Decco 65 DAC observations

"Obviously, the Sabre DAC should push a better sound, correct? WAY better? "

Not knowing much about either DAC in play here, why should the Sabre DAC necessarily be better?

1) there is a lot of variability in how DACs sound.
2) the determination which DC sounds better can be largely subjective depending on listener preferences or expectations. That's why no one size fits all.

Its also possible that your digital connection from Arcam player to Decco is introducing more jitter than internal coupling to DAC in the Arcam. There could be many reasons why this could happen. Not all digital connections between two pieces are created equal! If it were determined hands down that ESS Sabre DAC is not performing as well as it should somehow, then this is probably the most likely reason.

The arcam alone is likely no slouch.

I found the following on the Arcam site about it:

The 7SE uses a latest generation 24 bit DAC from Burr Brown and also features lower jitter levels and improved power supplies. Arcam has added an optical digital ouput to cater for the increasing use of minidisc recorders in addition to the standard co-axial digitial output. The overall sound quality is exceptional for a player at its price. The 7SE maintains the upgrade capability of the the Alpha CD players; the units can be upgraded all the way to the state of the art perfomance of the Alpha 9 CD.

This indicates DAC quality/performance could vary widely depending on upgrade level.

Also Arcam in a few models once licensed and used the DCS Ring DAC technology, which is/was no doubt SOTA in many ways + sells for a huge premium in DCS products. That DAC in an ARCam priced unit was way too good to be true at the time and did nt last long as a result. Still, Arcam set a fairly high bar at modest price to strive for at that point with its follow-up products.