Audio Research PH3 service, upgrades

A friend has a stock audio research ph3 phono preamplifier. It has not been powered on in a few years. My tech advised against powering it up prior to replacing some of the capacitors. The unit is super basic inside; I am interested in knowing of PH3 owners that have upgraded their units and/or simply serviced them in general. What brand e88cc/6922 tubes sound best, what capacitors, resistors, etc?

thanks in advance for any information
My advice would be to send it directly to ARC for service. They'll check the specs., make any cap and other upgrades (like new rectifier, etc), change out worn RCA connectors , and if you want them to do it, put in new tubes (or you can experiment with buying your own.) It would be money well spent IMO if you're thinking of keeping it.
The PH3 is not that old of a model. It sold for $1500 nine or so years ago and typically sells for $700-800 now. Other than playing with a couple different tubes, this unit should be mighty fine. I have really come to like the Mullard 6922 and 12AX7 tubes. With the PH3's somewhat forward presentation, a more balanced tube like the Mullard over the stock Sovtek would be a great benefit. If ARC replaces the tubes, you will pay more for the stock Sovteks than a nice pair of Mullards here on Audiogon.

Just because the PH3 has not been powered on for a few years, should mean nothing. I have had several ARC models much much longer with all orig parts and they worked fine. There's no need at all to spend a dime on replacing connectors either. The RCA connectors ARC uses should last a lifetime. It's not like this was a reviewer's model that saw many IC swaps on a daily basis. And even then, these connectors are fine.

The minute you spend anything on upgrading this unit, you will never see the cost come back to you. The PH3SE was the same unit with many improved parts. Why not try this PH3 with some different tubes, make sure it works mighty fine and then look into a more refined model. The PH5 is getting a lot of praise out there.

I had a number of ARC products updated and serviced. Being 3 minutes from ARC was a benefit as I did not have to worry about UPS or FedEx destroying anything. But this is always a concern...and shipping costs back & forth add up fast too. ARC service is first rate, but it adds up fast too. So my advice is try the unit, even with its stock tubes, and I think you will be mightily surprised.

Agree with what Jafox recommends and I would add that if the unit has not been powered up for several months/years the cheapest insurance is to power it up slowly using a Variac. The advice I got was to start at 10% voltage (i.e. 12 VAC) and increase every 10-15 minutes an additonal 10% until full voltage is reached. This will reform the capacitors and prevent a catastrophic failure. I'm not saying you will have a catastrophic failure if you just plug it in, but like I said it's cheap insurance!
If it is not too late/you still care, I used the Tungsram 6922 in both my PH-3 and LS-15. For me it opened the soundstage, and dramtically extended the base vs the stock Sovtek 6922's
I have many Audio Research pieces, I have four PH-3's and they are fine phono stages for a very fair price....Don't worry about just plugging it in , the modern caps they use are much better than caps of the past....Audio Research service is nothing like it was before the new owners took over.....I just sent two pre-amps in for service and the repair estimate was over 1200.00 ....These pre-amps both worked, but needed some ongoing service, caps and the switches cleaned......When they were returned the remote was missing on the 5500.00, LS-10 line stage and they don't make them anymore, so I now have a very expensive line stage that has no remote....That is my experience with the "new" Audio Research service..