I bought the AKG K702 65th anniversary editions recently, and I already own a Xonar DX to act as my DAC/source.
As such, I am looking for a good amp, preferably not too expensive.
Any help would be greatly appreciated :)
I would think the cheapest (but still good) would be a Schiit Magni or O2 ( Objective 2) or Bravo Ocean (tube).
Might read up and ask on this thread about amps for the K702.
In the worst case, a ringing that never stops. In mildly irritating cases, vibrations and tapping that occur anywhere on the desktop where the amp is located are picked up by the tubes and included in the signal. Microphonics is a tube defect. Sometimes tube dampers help, but they're far from optimum. Subminiature tubes are known to have this defect, because they were not designed for audio at all (many were bomb fuse circuits during WWII). Note the big black rubber grommets (tube dampers) on the tiny tubes in this pic (from Oatley Electronics). They're designed to "cushion" the tubes from external vibrations:
Any tube can have microphonics, but it's much more prevalent with some tubes (subminiature) than others. For most audio tubes, it's a defect that might afflict 1 out of every 20 or 30 tubes - or even less prevalent. For some non-audio tube types, the chances of microphonics with any given tube is much, much worse.