Dedicated 20 amp lines/should i use a sub panel

Thanks dill, makes sense as not to add any extra contact points. i had just thought that by adding the sub panel the 3 dedicated lines would be better isolated from the rest of the houses electrical devices.

It is good not to introduce additional wiring and contact points, but...

it is also good to isolate the whole thing from any noise that reaches the main panel and a sub-panel could help with that.

I ran 2 x 20amp runs on 10 gauge from 2 side by side breakers for monoblocs. I ended up not using one of them because of a hum loop. Let us know how you get on.

I don't think there's a big benefit, besides wiring alone, but there are some interesting options in terms of noise suppression and balanced power at the power panel.

Check with your electrician.

My electrician recommended a subpanel and I'm so glad I went for it. His reason was my main box was a mix of old and new wiring and I was hearing noise thru my existing line to my Hifi rig.

He knew what he was doing since now I have two separate runs with no metal staples used, with two Hubbell receptacles grounded at the subpanel. He also added a second 8' grounding rod.
There is absolute silence thru my speakers now, and I'm using all tubes. I was able to remove one of my power conditioners since the noise floor is so low.