Best way to drive Sennheiser HD600's?

So I just got a pair of HD600’s and I’m loving them. I find a bit tedious the fact that I have to be constantly moving them around from my PC to my Digitakt, MPC etc. I have a mixer (which is connected to my sound card and other gear) but the headphone output is not loud enough.

So my question is, should I get an audio interface (such as a 6i6) so I can have both my headphones and monitors connected and be able to chose where I’m monitoring from? Is this audio interface going to provide enough juice for my 300 Ohm HD600’s? Or am I going to need an amp?

Where do you plug your headphones? Audio interface or straight into your gear?

A headphone amp might also be a cheap solution, no?

i was recommended the SCHITT - VALHALLA headphone amp. nice cheap amp, but sounds AMAZING. lots of bang for your buck. if you get its companion DAC it sounds even better.

picked one up for my Grado PS1000s…sounds unreal

It’s an old Yamaha MG10/2 mixer. On my soundcard’s output I have a 2 to 1 splitter, in which I have a cable going to my mixer and a headphone extension. On my headphone extension the headphones sound ok, but plugging them straight into the mixer gives a lower playback.

In this setup I can’t choose where to monitor from (headphones or monitors), it’s either both playing together ir I have to manually turn off my monitors or unplug my headphones.