Preamp Noise with High-Efficiency Speakers

I too have super sensitive Avantgardes (107 dB Duo Omegas) and run a tube pre and tube amps (as well as an AMR tube CD player, and analog with tube phono stage) with virtually zero noise - one must put their ear right up to the tweeter horn to hear the slightest hint of tube rush with no music playing, even at "generous" volume settings.

I would definitely check for ground loops first, and ensure that you have clean power (I run dedicated 20A circuit for my amps/sub amps and dedicated 15A circuit for my pre and sources, the latter through a Shunyata Hydra).

A tube pre with separate L&R gain controls will allow you to dial in the sweet spot of gain for your rig, as well as providing a de facto balance control, handy in asymmetrical rooms.

What's wrong with just using the AMR DP-777 with it's volume control or just use a passive preamp like Lightspeed Attenuator or similar with just a pot in a box, no noise with passive pre's. And as you have such high sensitive speakers you are throwing money away using an active preamp, unless you like the colouration they can give.

Cheers George

Passive volume controls and digital controls offer their own colorations. You are certainly not throwing the money away if the active preamp delivers on its promise. They can be plenty quiet on high efficiency speakers if the system is set up correctly.

Whart and Triode: I may have to go through the lengthy process like yours to eventually get rid of hum/noise. I was thinking about Granite Audio Ground Zero yesterday.

Georgelofi and Atmasphere: There are pluses and minuses using an active preamp, and endless threads/debate about going preamp-less. I am fully aware that in recent years digital front ends have better and better output stages capable of interfacing power amp directly; and before I fix everything I have to live with the AMR DP-777 driving my power amp (Audia Flight 100) directly. But you never know what you are missing, and I've witnessed many times a good active preamp can do wonders to a system.

Ying: Just keep in mind that the Granite Audio thing is not really a total solution, but in some ways a 'band-aid'- and i had mixed results with it; on some system configurations with different amp and preamp it seemed to work better than others. Just sayin'. And, you really need two people to work it successfully- one to throw the various switches (exponential combinations, when you add in what gear you join on the same 'path') and one to listen to results. You also may have to order more of their grounding cables and longer lengths to get it to connect to various components. (and yet another variable is not connecting to some components). I bought mine back in 2007 or so, it is far cheaper than some of the esoteric external grounding solutions available today, but imagine if you are handy, you could come up with a DIY solution. ( Ralph or Almarg might chime in here), you may be fighting potential grounding problems within the components themselves. None of this is easy, but it's more labor than anything to get it sorted.
Let us know what you come up with. I hate hum!