A New Ground -- Benefits of introducing the Synergistic Research Active Ground Block SE

I’m fascinated by this subject but have not thrown money at it. I messed around with star grounding in the past, did have one of those cheapy Granite Audio boxes that, to my understanding, was like star grounding everything at one place, but gave you switches to mess with the ground planes or impedances of various "channels’ of connection. I used it temporarily to ameliorate some hum, but the answer turned out to be my Lamm ML2 amps. When I bought them, the previous owner had disconnected the wire of the circuit board to the chassis and no hum, but when I sent the amp to Vlad to go over, some years ago, it came back with the hum. We looked and that little wired had been replaced. I don’t like cheating the grounds, but that seems to be the only solution (unless I get into the unit which I’m reluctant to do).
I have a new isolation transformer that was just installed --a 10kVa and it doesn’t really address ground since, by code, it has to be connected to the main household ground (a Ufer, installed when this house was restored, along with all the electrics). I did install a separate or "clean" grounding point within the room- not isolated-- one of those big copper bars with holes (looks very much like the top of the passive Synergistic ground block) that runs back to the main household ground via a 4 gauge cable. That, obviously, didn’t make much difference either. The electrics for the hi-fi are dedicated, and pull from a subpanel to 20 amp hospital grade receptacles using 10 gauge Romex. The feeders are 4 gauge.
I gather Ralph is talking about inter-component grounding differences that cause the hum or weird ways of grounding a particular circuit within a piece of gear.
I get the concept that external star grounding as a supplement (not as a replacement) for grounding equipment could theoretically quiet a system- my speakers are very sensitive at 104db/meter so you here every gremlin.
I did get into a discussion with an EE who said the isolation transformer does zip unless it has an isolated ground, but I gather there are still benefits to nasties on the hot and neutral.
My plan was originally to build a separate building in the backyard of this house-- we had the feasibility study done, and zoning pre-approvals. In the meantime, the system is installed in a large loft space at the top of the house and it isn’t bad. In fact, even the current out of the wall-- the so-called "dirty power" is way better than what I had in NY metro-(up in the country), quiet, more stable, no brown outs (so far) despite the considerable heat here in central TX. The room is made of shiplap-- old planks (although covered with drywall in this upstairs loft area) and seems to sound very good, though I’m only just beginning to dial in the system. The whole grounding thing is a bit of a puzzlement--I should ask Vlad- since he has always been very responsive to me, and I love the sound of these old amps. Otherwise, I haven’t heard the really fancy external or supplemental grounding boxes but call me intrigued.

Thanks, Ralph. I know it is grounded now, but will hum unless I lift the ground. I do have a decent meter and will poke around without opening up the units. 

@lewm thanks. I do believe there is something already wired into the connection between the circuit ground and the chassis/main AC ground receptacle inside the amps, but I don’t feel comfortable messing with it. I will continue to investigate, perhaps talk to Vlad- since I’m sure this came up at one point over the years. I suspect it may have something to do with the woofer amp that is part of my Avantgarde Duos- I think there is something internal I could do with the speaker (have to check the manual on the speaker, but I think that is user-permitted), not sure.
@atmasphere Ralph- using my Fluke, I measured .2 at the ground pin on the amp cord, unplugged. Measuring at the RCA input to the amp, with everything, including speaker cable, disconnected, the shield or collar side of the RCA jumped around radically, nothing nearly as low at the ground pin, but high voltages, lower voltages- and no OL type reading on the meter suggesting it is "off scale." Why is that so? (FWIW, I use the XLR input on the amps, not the RCA (though these amps are not a balanced design, i just prefer the integrity of the connection).
@lowrider57 I can offer this much-- the Granite Audio as far as I know-- mine’s in a box somewhere- is very much like an external star ground that supplements but does not replace the AC ground. It does allow some switching of the impedance of the grounds depending on which channels on the back you plug the wires into, and how you position the switches relative to each other. I don’t think it does much else. I’m also not sure how star grounding overcomes some inter-component grounding problem within a system if everything is still hooked up to the normal AC grounds, but at one point, it did minimize noise when I was first setting up this system in NY some years ago. Beyond that, I cannot say.
The passive Synergistic looks very much like a standard copper bus(s) bar, mounted in a small box that may have some additional passive material in it. (The connection to the wall is only for ground, not to power it, I believe, much like the Granite Audio).
I cannot speak to the SR Active device, but there are, as you know, a host of things available now as @folkfreak mentioned in his OP.

I will talk with Vlad and look at the Avantgarde manual re the internal ground settings that are user adjustable. My bet is that’s where the issue is coming from. Thank you all. I’ll continue to follow this thread, not for my issue as such, but for general learning on the grounding subject, which is (strangely) fascinating to me. Disclaimer: I do not mess with electricity - got a healthy respect for it. But trying to decode the EE level discussion and make sense of it in audio applications is no easy feat sometimes (at least for me), even leaving aside the ’wire is wire’ approach. The Gutwire thing mentioned above is also pretty fascinating, but I need time to read 6 Moons. Maybe I’m just slow. :)
regards,
bill hart