Heed CanAmp dedicated headphone amplifier.

Takes signal from your amplifier's "tape-out" socket, and will make your headphones sound much better than the vast majority of sockets fitted to pre or integrated amplifiers. Most of which are no more than a box ticking exercise. I now have a decent streaming pre-amp which sounds very good with headphones. I have had this since 2020. It works flawlessly and is in excellent condition.

These are approx $1,000 new, so $450 sounds a fair price.