I have been using a PH7 since 2009, having had a PH5 before that. Mine developed an issue with either a cold solder joint or a weekend solder joint and so on occasion I get a loud hum when first turned on. I know where I have to push on the board to get rid of it. I sent mine in for the upgrade. I thought would've been repaired BUT it went to the upgrade w/o going through the proper procedure for repair. Hence my issue wasn't cured. But the upgrade is worth it. The (3) 6H30's were all aging faster than they should have and all at different rates. After the upgrade you're left with 1-6H30 and a 6L6G/5881 plus the 4-6922. I have rolled many a tube to get the sound I need. I really like the PH7 and wouldn't go with an all 6H30 ver. like the newer units. I have switched to the EH 6H30 gold pin versions and they are much better, warmer with a more even top to bottom sound. The 6L6G/5881 also rolls well.
I also found that the unit sounded better with the top off, so I have mine velcro'd on and pop it off for serious listening sessions. I wouldn't trade the RC cart. loading for anything. Every once and a while it won't turn on either by RC or front panel. So I have to unplug-plug-in the cord from the back and all is fine. ARC didn't seem concerned about it and told me what I was doing was what they recommend. I'm not sure why it does this and ARC never said why either.
I also found that the unit sounded better with the top off, so I have mine velcro'd on and pop it off for serious listening sessions. I wouldn't trade the RC cart. loading for anything. Every once and a while it won't turn on either by RC or front panel. So I have to unplug-plug-in the cord from the back and all is fine. ARC didn't seem concerned about it and told me what I was doing was what they recommend. I'm not sure why it does this and ARC never said why either.