Thoughts on Audio Research D70

So the verdict for my unit is:
Faceplate is dinged up and dented. Supporting bar bent. I cant get a replacement from Audio Research as they are out of spares.
Seller graciously offered a partial refund which is very nice of them.
The 1A fuse popped several times and made me worried the screen regulator circuit might have hidden issues. 3 x 1A fuses and a trip to the local store with a tube tester I am fairly certain it was a bad 12AT7 that tests weak on the tester. Replaced it and I have powered it up 10 times since with no issues.
I am hoping that the fuse pops were just a problem with the tube.
Since the unit is of late vintage and confirmed to be a mkII I think the lytics are still OK.

I meticulously adjusted the diff amp balances and bias and now it sounds better than initially, and so far the voltages (esp screen regulator output I am cautious of) look stable.

Over sound is that it's really foggy and a bit slow. Crank it up and I notice glare and roughness.
Space is real tight for any cap mods. Auricaps will fit but how much better are they than the Rel + Wonder paralleled.

A friend has a pair of Reference 300 that's in the store room for at least 4 years now since the last power up. Maybe this little project, if successful, can get him to power them up and play again.

@HifiGeek1: What do you think of the recent frenzy regarding those whatever 50 years treasure funny black bottles and the whatever black sable 6550s? PM me if you want to avoid flaming :)

Johnsonwu, sorry to hear of your travails. I would say that there must be something still wrong with your D115M2 if it sounds foggy and a bit slow.
Did you replace all of the tubes and check the caps?

All tubes are known good tubes from my collection. All voltages were checked and verified AOK.

I have no way of checking how good the lytics are cos I dont have a big cap meter and I dont want to pull out the lytics.

Foggy is expected of the Rel-cap/Wondercap combo, as I have over the years owned quite a number of Audio Research amps. No surprises there. With this amp, everything is like 95% there but not quite excellent. Nothing annoying, but nothing that leads me to say, wow this track plays good.

CL120
VT150
CA50
VT200
CL150
VT130
and I might have missed a few...
Most of them I ended up redoing the coupling caps with Infinicap-S, Dynamicap, Auricap, or Jensen (wish I had tried V-caps and worked on the all-tube models more before I sold each of them one after the other).

Problem right now is that space is at a premium and its very difficult to put in premium caps into this amp due to their size.

'Foggy', certainly isn't a term that comes to mind when I listen to my ARC!
Not sure what you are hearing, but if 'Foggy' is a factor, then I would suggest you look elsewhere in the chain for the offender.

No flaming. My attitude about spending gobs of money on NOS tubes is kinda like buying expensive flowers. Sooner or later there going to die...LOL I'm not a big fan of NOS output tubes. The D115mkII was designed around the Philips/Sylvania 6550. Look for a set of those. BTW just because the voltages are ok on the amp doesn't mean the voltage regs are quiet. That's important too. Noisy voltage regs. have a negative effect on that amp. Also, there is a B+ reg and a buffer reg. Make sure the voltage differential is the same or close to the circuit diagram. If the power supply caps are more then 20 years old, replace them. All new caps will make the amp sound better especially in the bass provided there's nothing else wrong with it. There are a few axial caps scattered throughout the amp. Replace those as well. On top and underneath. There is also a 27K ohm resistor near the main filter caps. Make sure it measures 27K. Those do open with tube arcs. There should also be red cap plugs on the capacitors. The support bars always get bent because people try to lift the amp with them and their aluminum. You can remove them and straighten them out a bit to get some of the kinks out. Use a rubber mallet, however the rack handles will come off too. Do one at a time. I strongly suggest you make sure that amp is in good working order before you attempt to modify it.