I decided to replace the wiring inside the cabinets. I found many great reviews for the Belden 9497 (top picture) and it was used by Shindo Labs. Trouble is it is thin and only good for low powered valve amps into efficient speakers, it just wont handle larger current. I decided to make my own beefier version of this cable and purchased some 2.5mm square, marine, tinned, thin wall cable. I twisted this together using a cordless drill and as you can see from the two specs it is very similar, using similar diameter strands just more of them. I tried this out as a speaker cable running from the amp and it is very natural sounding with phenomenal bass, so I replaced the stock internal cables with this and while I was at it, bypassed the level controls and ran the cables along neater paths and not bunched together which could result in crosstalk.

As it turned out I didn't like this cable as it high lighted some distortion I was hearing in the upper mids.

I took it out and replaced it with plain 2.5mm OFC that I stripped out of some old Van Damme tour grade cable that I had lying around. This was much better at concealing some of the distortion.