The secret to a great amplifier...

Tweaks that I've liked: 
SR Orange fuses (not subtle) 
Highend Novum PMR resonator (subtle) 
Tweak Geek Stealth passive conditioner (used, subtle) 
DNM cables XLR x 2 + speaker cables(subtle) 

Tweaks that did nothing for me:
BDR cones under preamp and amp
SR FEQ + HFTs (10)

I'm lucky enough to be able to afford to try these things.

At this point, I have two more tweaks on the way:
PPT omega emats 
High Fidelity Cables MC-1 pro

Stick a fuse, any fuse, in a crappy amp then come back and tell us the amp is now great.

We will wait.

Stick a fuse, any fuse, in a crappy amp then come back and tell us the amp is now great.

I don't think anyone's said, or even inferred, that.
As far as segues go, it's better than most.

All the best,
Nonoise

Tim, they come with a full 30 day return guarantee. Hardly any get returned because they work so well. As redwoodaudio notes the improvement is not subtle. Its roughly equivalent to a good $500 power cord, interconnect, etc.  

Redwoodaudio, You will enjoy the eMats. Very similar improvement to what you hear with the Orange fuses, only even more smooth and natural. Not the kind of thing that hits you over the head, more you notice many things sound much more real.  

Try them different places. They seem to work best near powerful fields. They can be cut up into strips and wrapped around outlets inside the box, or around speaker magnets, or even speaker cables and power cords. I have them practically lining the insides of my conditioner and step-down transformer boxes, and wrapped around most of my cables.

I'm surprised ten HFT did nothing. Mine went up one at a time or in pairs, and it was easy to hear not only the improvement each one made but to fine tune it by moving them slightly one way or another. One time I tried one where I thought it would be good, but it actually made the sound worse. Never had one where it made no difference at all.

Stick a fuse, any fuse, in a crappy amp then come back and tell us the amp is now great. .....

.....I don’t think anyone’s said, or even inferred, that.
As far as segues go, it’s better than most.

That’s exactly what the OP is pitching.

if I wanted to make some bucks, I’d put these is cheap OEM compnents and start letting the accolades and purchasers come calling.