Thoughts on placing amps on stone/tile base

Amp stand, piece of glass, wood block, or surface table all work fine. 

Vibration control is a concern and yes everything sounds different. Glass, tile and stone all can be used but they ring and will impart hardness and glare. Wood is better and the sound you get will depend on the type of wood, thickness, and construction (laminated, slab, etc).  

There's no reason not to put them directly on the floor. But if you do want something that works really good without spending much Nobsound springs are only about $30 a set of four and are phenomenal value. Way more improvement than you would expect for so little money. 

Much better, but also much more expensive, Townshend Pods are springs that are much more carefully engineered than Nobsound and deliver a whole lot better sound. Much more extended, dynamic, and true to tone and timber of the instruments. 

+1 on the nobsoud springs MC. They outperformed a set of isoacoustic pucks under my coincident pre head units. After that I just reflexively put them under all my equipment. You can remove springs to adjust for weight.

We use a top o the line cutting board.
put several cherry stain coats on it.
looks nice. Keeps the amp out of a rack.

 Marble, wood, tile, etc.....it all sounds the same. 
 A home improvement store is fun, tons of outdoor concrete blocks, marble, etc, paint, or keep natural color, tons of stuff you can do, spending 300$ on a “amp stand” is silly.

 Get a nice thick piece of concrete, or wood atop a concrete/marble base.

 Enjoy. Keep it simple, don’t overthink it ,....what so ever.

Thanks for all the feedback. Just ordered a 3inch platform from Butcher Block Acoustics. DIY is fun but a project like this can take forever especially if I fret as much about the finished product as I do for my listening environment...