Confused on two points here:
1. If you don't know what jitter sounds like, why do you think it's conspicuous in your system?
2. How can your friends adjudicate whether you're enjoying it?
Jitter is a wide-band artefact: it's present in every digital transfer, but usually only an 'issue' in time/voltage-sensitive audio equipment. The solution is always the same: better clocking - better components and better protection of them from parasitic noise.
There are several clock upgrades available for your AT3500, but it's none too shabby a transport in stock form. Perhaps you don't like the basic signature of your DAC, or the horns are a bit bright and honky in your room. The only way forward is to try a few alternatives at home - and/or room treatments.
But in order to make a targeted recommendation, it would be helpful to know exactly what your system does that spoils your listening pleasure!
