amp for DT700 600 ohm version? can I plug it into my USB interface?

[Windows95]

My old brother gave me his Beyerdynamic DT770 600 ohm version, the Manufaktur version which is no longer availible, they look so cool. Unfortunately my USB interface has a broken headphone jack, it makes weird crackling noises. So many people complained about this unit having a very bad headphone jack. Sound quality is decent but built quality is cheap. Is this one:

 

 

 

 

So my idea was basically to get an amp like an Schitt or Lake People and plug it into the 3 and 4 TRS outs, and keep using my monitors on the 1 and 2 outs. Then I just leave the AK1 knob for 3 and 4 outs at maximun volume, and I control the volume with Schitt knob or whatever I buy.

Is this a good idea? Will my old AK1 be a bottleneck and reduce quality of sound? Which amp to buy?

 

Im very confused at this.

 

Also I have TRS to XLR cables, which I could I use, so I would prefer if the amp has XLR inputs. For some reason, Schitt uses unbalaned RCAs... im not sure if this will make quality worse or not. I wouldn't like to buy more cables anyway.

 

I do not understand how the numbers work when it comes to finding out if an amp will be enough or not for 600 ohm (I mean calculating mW, ohms, and all that stuff). Please help