Try all conceivable positions including counter intuitive ones before deciding as all rooms are different.  In my case after trying upward pointing I reverted to forward facing in the old piezo horns 5"-6" above the middle treble panel & like you stated in the reverse phase, or in phase with the Amplifiers + to + the OTA Quad 57's  being - to + please keep us up to date.  

Been having a very frustrating time with things Quad . Tried a pair of Aurex amps in bridges more and they sound very good indeed . Sadly they fitted with very sensitive speaker protection circuit so they cut out when you turn the volume up or when the next track is recorded at a higher level . Hoped that using some one thing audio widgets would help but sadly no difference . Real shame as within their volume envelope they sound amazing . So back to my NVA S300 which also sounds too class . This has meant I have still to get round to trying the super tweeters but no doubt that will happen soon . Just can not find any small horn cases to put them in . May have to just use blutac as temporary fixing till I find the right thing .

What can I say I am both lazy and tired . Have had a chest infection for about two weeks now and with age it seems to be more of an uphill battle to recover . Still not started anything yet with these super tweeters I going to make a real concentrated search for some form of horn throat to put them in and if I find something will feel inspired to start this journey .

I have 4 x Auva 70's under each of the Rupert stands, they are 70 mm in diameter with 3  Auva chambers the effect was immediate as commented on by Paul Rigby The Audiophile Man below.

"With the Stack Audio AUVA 70 feet in place?"

"Errr, blimey! I mean….blimey! I felt like I needed to suddenly sit up straight and pay attention. I actually did do that, without realising. As if the music had just woken up. The entire soundstage was suddenly precise and focused. The mids were crisp. The treble was exacting. The bass was even tighter than before. It started and stopped on a pin head. I really didn’t expect such a change in the sound."

"Because of this almost mathematical precision, the supreme focus, the removing of even a hint of wooly bass or slightly meandering mids, everything sounded clearer now. Vocals, the actual lyrics, were more easily understood. Nothing got in the way of the delivery any more.

To repeat though, I didn’t even know it had. I thought everything was hunky dory. I thought my system sounded pretty good, to be honest. These feet told me I that I had been living a lie, all this time."

The eloquence & descriptive ability of Mr Rigby far exceeds my own, however the loose particles in the Auva chambers that rub together turning vibration into heat do settle over hours & days into their most efficient state. I tried 4 x Auva 50's under my Hydraulic Reference turntable, initially there was an improvement I then fitted 4 x new KT 120's power valves to my Atlas Magnum amplifier & changed the 3rd valve a cathode follower in my Croft phono stage fitted with SUT's by my dear friend Mark Manwaring-White utilising the original Croft circuits. I realised as I have written elsewhere for the very first time that I prefered the digital side to the analogue.

I removed the Auva 50's from under the Hydraulic Reference turntable, the result was stunning back camme the life the sparkle & bass that I had dreamed of from the Hydraulic Reference,Hadcock GH242 Silver plus arm fitted with an XTC low slung counterweight & Hana ML cartridge. It seems that the Auva 50's once they were at their most efficient absorbed vibrations so well that they sucked the life from the unsprung Hydraulic Reference turntable which became so obvious after new valves etc with it being reinstated on to it's 3 Oak Cone feet on to the massive paving stone turntable shelf the life & vibrancy returned, It seems that with a sprung deck results would be different as I have read elsewhere.

I have 4 x Auva EQ 1'S under my 7kg MC7R preamp & 4 x Auva EQ 2's under my 24kg Atlas Magnum amplifier & 4 x Auva 50's under my Croft phono stage & 4 x Auva 50's under my Cambridge CD4se that I use as a transport. The improvement they have wrought is a cumulative broadband improvement, through to my mind the Auva 70's under the One Thing Audio Rupert stands my One Thing Audio Quad 57's sit were nothing short of a revelation. My system is now sounding exceptional whether digital or analogue I'm am very with the Auva's inclusion.

I end with more comments by Mr Rigby "Before this test, I considered the Quad 57s – for the price – the best speakers in the world. Bar none.

Since I added the feet, that estimation has gone upwards!" I have to agree, Mr Rigby also wrote "I expected some sort of improvement from the Stack Audio AUVA feet sure but nothing, nothing in sonic terms, quite like this. The sheer level of precision from the music now was quite outstanding. For my HiFi system, at least, it felt like the last ingredient to make the entire HiFi chain click into place. It’s almost like my HiFi system needed a big nudge to give it that sense of clarity – and I didn’t know. I didn’t know that was even necessary until I tested the AUVA feet."

"The largest and most dramatic improvement was moving from basic feet to the 70s. That was a shock. Saying that, the move from the 70s to the 100s was a move to ‘proper HiFi’. High-end HiFi. HiFi that nods towards the sound and says, “Just stop what you’re doing and..take…a…listen…to…thisss.”

About Auva 100's " Differences, if any? Lots is what I’d say! But hear this, moving from the 70s to the 100s is to move from excellent hifi to truly high-end HiFi. And I mean top-of-the-line. It’s like moving from an exceptional boron cantilevered cartridge to a cartridge packing a sapphire or even diamond cantilever. That sort of standard."

Cogitating is over  Stack Audio Auva 100's now in place under the OTA Rupert stands & OTA Quad 57's.  After 5 + hours listening, my take so far is, even more natural than the Auva 70's or indeed the Auva 50's, at the moment bass not apparently deeper however more definition & separation between drums & bass guitar or Indian Jori (wooden drum) & Rudra Veena (long string instrument with a large gourd at each end) deeper sounding.   

Electronic music like Tomita or deadmau5 I can discern the previously single sounding deep bass notes are overlaid with 3 or more frequencies giving an almost  palpable texture to the bass,  Virgin box live recordings have a more natural quality now stepping away from HiFi to real performances I have written when listening to Norah Jones at Ronnie Scotts using the Auva 70's my table was 20 feet away my table is now even closer & I can hear  the knuckles of the double bass players hitting the bass. 

The treble & mid's are cleaner voices both male & female sound real,  where applicable the acoustic sounds natural & there is more to come the Auva 70's took 100 + hours for the micro granules  to settle the Auva 100's are an improvement even before 5%  of that time.

In answer to a sceptical comment on another forum regarding burn in rather than settling. My reply was as follows.

Is burn in real?, well without opening a wasp's nest re components/leads etc. Reading the literature & watching YouTube & talking to Theo Stack on the phone. My take/thoughts on how they work are...

In the case of the Stack Audio Auva chambers, including those with 1,2 ,3 & 5 chambers, each has a layer of multiple types of micro particles (patent applied for) including Tungsten if you shake any Auva near your ear you can hear a soft rustle, whilst the particles are very small it takes time for the particles to settle since the vibrational energy is quite low similar to a Chladni Plate where a frequency forms a set pattern at a single frequency when brushed by a bow changing the pattern with slower or faster bowing thereby changing the frequency.
The Auva chambers are subject to the full audio spectrum at once & it does seem to take a while for the particles to sort themselves out creating heat & absorbing vibration. The Auvas are made of Aluminium the stainless steel adapters etc are non magnetic (I tried a magnet).

An observation :

I Have found the dynamic range has increased since adding the Auva 100s, my wife (with tinnitus) has gone out to meet a friend/s.

The Auva 100's are as I believe still settling. I'm Listening to last nights prom & there is a wider gap? space? (can't quite find the right word) between the quiet notes/sections & the peak of crescendos ie the quiet parts like foot fall & loud parts with the orchestra giving its all.

Any other Auva users out there how say you.

Just thought I would add that my comments can be seen as semantics the important part that is being said is that these supports change and improve over time . What we call or describe them as is just trying to not confuse those who are familiar with electrical burn in this not the same process but it is a comparable effect .

I have heard both the Black Ravioli (of which I have many) and the Auva (of which I have four) settle and improve over the course of a week or so. The Auva have been positioned and left alone. The BRs seem to respond well to further weight being placed on top of the component. That's why I have so many Schramm weights, too.

I have just tried adding a heavy mass to the lowest (unused) shelf of my tall table supporting EtherREGEN, AfterDark clock and 2 x JS-2 power supplies, all on Auva CSA2. I'll let you know.

The thought of 'mass loading' my speakers, which are on Townshend Podiums, did make me laugh out loud. They are already 160kg each. How much more mass did you recommend?

Seriously, they each have 30kg of lead shot in the lower compartment.