Just search c-notes and look at pics. Tons of builds here.

Only 6 years old? I got 50 year old headphones. Pads are cheap. No reason to disappoint yourself with new headphones.

I was trying to think of a higher end company. 1st one that popped in my head.

Just use another service. Too much red tape dealing with Apple on anything. 256kbps is a damn MP3. Not lossless. That file should be 10mb per minute roughly. Or they use similar tech like Tidal MQA to fold the file into smaller files. Probably don’t want it used with Windows so no one can figure out its a scam like MQA.

They can be whatever they need. So long as the hardware that supports the DAC chip. Isn’t a complete pile of junk.

Also have to remember that electronic parts are sold based on their production quality. A perfect DAC chip isn’t going in a $50 POS Chinese made DAC. They get the ones from the trash cans. The good chips go to Emotiva and Meridian etc. The premium brands.

Nothing should change the sound. DACs job is to covert to Analog. The amps only job is to amplify. Both need to be low THD components. The amp should have more than enough power to drive the speakers to their max without being over-driven itself to the point it produces distortion that can be heard. So if the HDs require 500mw RMS and the amp puts out 1000mw with 1% THD. The HDs would only need half of the amps power with less than 1% THD. Should be nice clean power. Also the resistance load on the amp needs to be that rating. If you have 300 ohm headphones. The resistance would be to high for the amp to make half the power needed to drive the speakers to max. The amp would likely be driven past 1% THD. Start adding distortion and doesn’t have enough juice to support bass.

This is basically how any size amp and speakers work. Headphones aren’t special.