I recently asked Lloyd Walker how many miniature jars of his Super Silver Treatment contact enhancer have sold to date. "Something on the order of 4,400" he replied, adding that "only one was returned, by a guy who builds his own cables and speakers and tested it in mono." That's quite the consumer endorsement for an affordable tweak.
Some Internet posters recently expressed disbelief and mockery that application of Walker's Extreme SST could transform a $40,000/pr of tube monoblocks from sounding mediocre to excellent. Before you consider matters further, this does indeed reek of hyperbole, mysticism or plain-old bullshit. But think about it. Unlike with a transistor amp where the output devices are hard-soldered to the circuit, tubes (which in some cases see extremely high voltages) simply slip into sockets. Does it not stand to reason that the integrity of those slip-on contacts becomes vital to audible performance?
Say you have an EL-34 push/pull amp with tube rectification, four EL34s per side. That's 8 x 7 pins for the power tubes alone. 56 contacts. Now add four 9-pin small-signal valves (two as phase splitters, two as drivers). That's another 36 contacts. Now add two rectifiers, say 5AR4s. That's another 10 contact pins. You're looking at 102 vital circuit junctures that are not hard-soldered at all but medium-tension slip contacts. If your power tubes be 845s, 211s, 572s or 1610s, think 1000+ volts on the rails. Good engineering would want a perfect solder joint on such connections but tube maniacs are stuck with often oxidized pins and loose tube sockets.
If you inspect metal contacts under a microscope, you'll see pitted surfaces which, when placed one atop the other, don't make contact over the entire area at all. That's why upscale AC contacts from companies like Germany's HMS use soft copper and high-tension fittings. The latter deform the soft copper under pressure to "spread out" more evenly. This makes better contact and lowers contact resistance.
All tube amps are sorely compromised when it comes to how their output devices are socketed rather than soldered into the circuit (and screw contacts would arguably be superior to avoid having signal pass through globs of solder). Now factor in that many NOS tubes are 50 years old and their pins in anything but pristine condition. Anyone who has ever taken the trouble to try it will already know that sanding your tube pins to a mirror finish and applying something like Walker Audio's SST to "fill in" molecular pittings and abrasions and inject a highly conductive layer makes an audible difference far in excess of cost and effort.
Solid statesmen simply cannot duplicate this particular experience because their output devices are soldered. They still can and should treat all their RCA pins, bananas, spades and AC blades and will notice substantial improvements. But none of those will be as drastic as increasing conductivity of active output devices in valved components. Again, in our above EL-34 amp example, we talked in excess of 100 circuit junctures. It takes no genius to predict that addressing them would net substantial dividends. Let transistor guys cry foul or impossible all they want. They're simply incapable of appreciating this particular tweak application because their amps don't suffer high-voltage slip-on connections.