Hegel H300 still worth getting?

Depends on how good the H300 price is.  I have experience with H200, H160, and H360, and if you are using the amp for 2-channel listening, then I would strongly suggest H160 for around $1,700 used.  If you read the Hifiplus review, you will see that H160 actually sounds better than H300.  

No doubt Hegel makes good products. I was especially impressed with the H160 though. It had no trouble driving my Von Schweikert Endeavor E-3 mk2 speakers. There was never a time that I felt there wasn’t enough power. Then I tried the H360 which puts out 250wpc, and of course it sounded better than the H160, but it is twice as good as the H160? No, I didn’t think so. My only guess is that Hegel really did wonderful things in these 2 amps with the SoundEngine2 technology. The newer line of H160/H360 does sound significantly better than the H200. That’s why I wouldn’t recommend the H300. But again, I’ve never heard the H300 before, so I can’t comment on the H300. For the price/performance ratio, H160 is hard to beat. I also don’t use the internal dac because I have a Lampizator Lite 7 dac.

I had the intermittent transformer hum when I had my H160 and H360.  The humming would go away after a while.  I believe that's normal.  If it stays humming all the time, then it may be AC line issue.