Various questions from someone new to analog

[Coyote-X]

Your welcome!

I have a KAB record clamp and decided that I prefer the sound without it.
I am considering getting the Ringmat someday people here have good things to say about it.
As for isolation devices I replaced my Pro-Ject 1.2 turntable with the Technics which has excellent isolation and then put it on a 1 inch slab of marble on a freaking fish tank stand.
I can play the sh*t out of my system with practically no feedback what-so-ever.
A person can spend mega $$$ on all that stuff.
All I want in a table is one that sounds good at any volume especially very high volumes and I am happy.
I am no tweeker and dont want to be I just want to set it and forget it and keep the fun in spinning vinyl.
As far as the Gruv-Glide the record must be clean prior to using it.
once applied it will not have to be treated again for quite some time.
The Gruv-Glide will bring out sounds hidden deep in the grove sounds you never knew were even there before, amazing.
Heck its an amazing product a DJ Friend of mine turned me on to it and I have been very pleased with the results.
Less surface noise, life-like vocals, reduced record & stylus wear, no static.

How do you tell when you're getting feedback and when it's just noise on the record, or distortion on the inner tracks? And how much vibration do you have to have to cause feedback? Is it because some people are running subwoofers in addition to regular stereo sound?

When I crank my system, just about everything in the basement including the concret floor vibrates to varying extent. With the volume at 50/80 (just over my normal listening level when there's nobody home) I can put my hand on the turntable itself and feel vibrations, while hearing some distortion.

I'm not sure whether that's because it's a small amount and the high volume is making it audiable, or whether it's feedback from the vibrations. With some older records or ones with high-activity tracks on the inner reaches, I can hear similar distortion at any volume on the inner tracks.

Also, my turntable is pretty modest compared to many here so it may be that it's simply not sensitive enough to pick up the extra vibrations? Maybe the stereo isn't powerful enough to produce such? I run a 5.1 JVC reciever with 100 watts per channel, currently only hooked up to two Infinity Entra One bookshelf speakers, circa 2002.

This is the way I currently have everything.