CD player, audio out, discrete vs. op-amps..?

It's "possible" that the op -amp could play a role in what you hear. I've read that they rely on generous amounts of NFB. A discrete circuit can be designed with little or no NFB used. Just a generalization(other varibles as well at play). The best test is to listen and judge the individual players of interest.

I agree with all of the comments by ZD, Bob, and Charles, and Alan's suggestion of tubes is of course also well worth considering.

I would add another reason for the likelihood that a player having a well designed discrete output stage stands a good chance of outperforming one which utilizes an op amp-based output stage. Since a good discrete circuit stage will typically represent a more expensive design approach than an op amp-based circuit stage performing a similar function, it can be expected that the use of an op amp-based output stage signifies a likelihood that cost minimization was a higher priority in the choices of the design approaches and parts used in the rest of that design.

Regarding NFB, I agree with Charles' comment, and conceivably that may be a factor as well, but I'll mention that the feedback used in an op amp stage is typically "local" (i.e., confined to that stage), rather than "global" as it often is, for example, in power amps. Local feedback being less likely to have adverse sonic effects than global feedback, everything else being equal.

Regards,
-- Al

"I recently read an article about the Pono player and that Charles Hansen did the electronic design.

The audio circuitry is fully discrete, meaning there are no integrated circuit chips of the sort used in every other portable music player. It's a bona fide high-end component.

And, of course, it has no feedback (global I assume). But, what if after all of this his circuit can't pass a hi-rez music signal? That's the goal of the Pono player and yet, it was never mentioned."

"The PonoMusic Store uses FLAC (Free Lossless Audio Codec) audio format as its standard, for compatibility, although the PonoPlayer can play most popular high-resolution music formats from other sources. PonoMusic has a quality spectrum, ranging from really good to really great, depending on the quality of the available master recordings:

• CD lossless quality recordings: 1411 kbps (44.1 kHz/16 bit) FLAC files
• High-resolution recordings: 2304 kbps (48 kHz/24 bit) FLAC files
• Higher-resolution recordings: 4608 kbps (96 kHz/24 bit) FLAC files
• Ultra-high resolution recordings: 9216 kbps (192 kHz/24 bit) FLAC files "

I got that off the Pono website. It looks like it will play high rez music.