Do the normal things for fans, if the LVPS fans are too loud, try replacing them with rated lower db fans, isolate them from vibration, perhaps add a resistor to lower voltage (don't know how safe that is though). I think vibration isolation is your best bed, the Marquee LVPS fans are directly attached to a very tinny aluminum box that likely makes alot of vibration noise.
Tim has a mod that he does that will quite the thing down quite a bit. He also does a few other things to it, to make sure you don't over volt the heaters on the tubes I think.... I have a 9000 and need to talk to him about this but until I get this thing mounted and figure out if I can live with the sound I am not going to worry about it. ( i believe the 8000,9000 don't suffer from the high volt problem).
If you do a search on this you should be able to find tims response to this
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