The reason Cary Audio changed the plate on top of the power supply to one without “foot indentions”, was to discourage people from stacking for the sole reason that sometimes the transformer radiated noise into the preamp above. When people would complain about hum being radiated into the preamp from the power supply, and we’re told to move the power supply away, they would question “then why are there indentions on the top plate for it to be stacked?”. So Cary Audio changed the power supply top plate to one without indentions so people wouldn’t stack them or question anymore. Thus, no more hum issues.
Heat typically wasn’t the problem although they do get hot because of the rectifier tube in the power supply. The power supply umbilical cable was made by Kimber Kable for Cary Audio and is pretty good non-shielded wire.
Some people change the rectifier tube to a solid state type (for sound change purposes) which also runs cool and can make the preamp sound more detailed with much tighter bass. It’s something to play with you like. I use SS rectification in mine using high speed rectifiers. Not HexFRED’s but similar. I had an old “Weber Copper Cap” that I upgraded the rectifiers in that just plugs into the octal socket in the power supply. You can use one of those made by TubeDepot or whatever. In my system I love the speed, imaging and detail it presents but every system is different. If you already have an overly bright sounding system you probably won’t like SS rectification on your SLP-05.
question for SLP05 owners:
Back when the SLP05 first came out, the (separate) power supply was designed so that the actual preamp part of the SLP 05could sit on top of the power supply. I was wondering if any owner/operators actually went that route, as I am thinking of re-configuring my listening room so that I can use shorter speaker cables, and placing the preamp on its power supply might make that transition easier. The reason I am asking, however, is that I have noted that the power supply gets really hot after a couple of hours or so of listening, and I am not feeling real great about having the preamp right on top of it. Therefore I was just wondering what the experiences of others has been.