My units are stock, with the exception of some dampening material I just stuck to the inside of the units,they're the Mid Mono model,and look different than your picture.
They can run 6L6,El34 and their like,kt88 and others,according to the manual.
They have a LED bias bulb and one pot that you use for both power tubes to bias,seems to work well, too.
Funny thing,when I first got them the other day from the FEDEX man, I put them in the basement and fired them up to see how/if they work, I was using these older Marantz HD series 770 speakers and the minimax pre,along with these new:
(TM) Planet Waves ,cablestation HI-Definition 24AWG 75ohm coax cable
That's what it reads on the Cable.
These cables have neat way to terminate the end with RCA plugs,you simply cut an end clean,then insert the RCA plug into the cut cable,it then touches the wire at the end of the cable,then tighten a screw that then drills/punches a hole to the shied part,thus locking down the cable. works good too.
The bass with these cables and the large Marantz speakers downstairs was thunderous,maybe too much.
ya, the Marantz have 12" woofers and my large book shelve speakers in my main systems are 6 1/4" BUT they still salute with decent power,why did the bass come across so much more down stairs and not up?
The only diff was these new weird cables, I'm going to try them upstairs and see if the result is sim.
I now, have these new cables hooked up to my sub upstairs, as I changed from speaker wires going to the sub, to RCA cables running from the pre to the sub.
I did notice that I have to turn the sub WAY down as more volume goes to the sub than ever before.
If I knew more about the wire and the ratings on it,I would probably have more of a clue.
These PLANET WAVES (TM) wires were given to me where I do work sometimes.
An Audio company (forgot the name) installs custom systems on these 50 million dollar Yachts, and I do the wallcovering work for the shipyard, Delta Marine. They use these wires for the audio and video in the yachts,as all the staterooms have custom home theater systems.
The rca temination were so cool how they came on and of so easy. Plus, you can buy the wire and within a minute have a decent interconnect at any length you want. Take the plugs off and put them on other wires if you want.
So anyway, I'm going to disconnect the sub and put these wires on the pre-out and see if the bass kicks up. Maybe theres something missmatched with these cables and too much bass somehow comes through,I'm going to find out.
The cables are Audioquest Diamondback that are running to the power amp now,and these have always been top preformers. I do know Quicksilver has there own cables that they recommend,that might be worth a try also.