Vandersteen updates and amplifiers

Seeking experience and advice. I have the Vandersteen Quatro Wood (non-CT) and have enjoyed them on a large variety of music for the past 7 years or so. I have been able to hear changes with improvements in upstream gear and tweaks. I use a Pass Labs XP-27 phono - XP-22 Pre and the good ol XA 30.5 to power the Quatro. Balanced M5 boxes.  

Two things recently elevated the performance of the Vandersteen's in my room. First was the addition of Isoacoustic Gaia I footers. I was pretty skeptical about using these as Vandersteen designs to couple the speakers to the floor. These footers are supposed to decouple. But I felt is was worth trying because the speakers are positioned on a suspended wooden floor above a storage area in my house. I had to use the more expensive Gaia I because the 110 lb Quatro has to be supported with just 3 footers. Also, I had to buy 8 not 6 footers. It was not difficult to maintain the appropriate tilt angle by adjusting the footers. Be aware that the rear spike threads are different than the front. After many weeks of use, I think they are a significant improvement. The quality of the imaging and the tonal richness of the midrange expanded to my ears. More palpable presence in the room, better separation of instruments so that you can hear into the recording better. The bass quality changed almost like adjusting the Q. The bass may be a little less high impact and certainly less is transmitted into the floor, but overall bass better integrated into the music.

The second change was the addition of an HRS S platform under the Pass XA 30.5. This is the only component of the system that is near the speakers and in the high acoustic energy zone. Improvements in detail and clarity were not subtle. Very impressed!

So, fellow audiogoners, what might be the next steps for me if I choose to stick with the Vandersteen sound. I hear good things about Vandersteen M5 HPA mono's. This would eliminate the M5 boxes and the Pass XA 30.5. For the same price I could probably trade in the XA 30.5 for a more powerful .8 series amp.  Anyone with experience want to share? I would also consider updating to the Quatro CT if that would be a similar jump in performance. The Quatro seems to be the right size for my medium/large room.