http://metroamp.com/store/product_info.php?cPath=23&products_id=499
Steve Miller's unmatched FX loop design in kit form. Works perfectly for all metroamp kits, vintage Marshalls and most any tube amp new or old with a little extra space in the chassis.
From Steve:
This is an entirely new loop, designed specially for Metro kits and specifically with these classic Marshall circuits in mind. The idea here was to make a loop that truly left the tone, and just as importantly the "feel", of a cranked Super Lead unchanged. To not be able to hear any difference at all. Those with fine tuned ears know that's not an easy task. Even "good" loops are still audible or effect the feel in some way. You work very hard to achieve a certain tone, a loop should NOT change that. A tube loop may "sound good", but an ideal loop should not "sound" at all - the goal of this new loop.
There is nothing else out there like this loop, it's a new design using unique high voltage devices that actually run at high voltage. These little devices operate much like an "ideal" tube, but without all the drawbacks of a real tube (i.e. installing and wiring up a new socket, potential heater hum, tube noise, limited gain, lack of headroom, "coloration", etc..). Hundreds of volts of actual signal (way more than needed) can be buffered to true guitar/pedal level, then returned just as strong as where it started- distortion free. This is something no 12A-7 tube loop could do, forget about your typical SS loops. These devices simply will not clip, will not add distortion or compress the tone in your Metro amp. Even the signal phase is preserved through the loop.
To handle the extremely stringent demands these loops had to pass, these special high voltage SS devices were the absolute best choice. Nothing else comes close.
......1 less thing to assemble
Hey, did the loop turn out the way you wanted it to? I am thinking of gettin one for my cameron modded marshall head. No problem with the room inside, just curious if you thought it was worth the money and effort? By the way, was there anything else you had to buy after you got the kit? Thanks. 
