
Before it was bought out by Fender, Groove Tubes offered a small range of very classy guitar amplifiers, preamps and power amps. This Trio is one of the second versions as it came with the new 3+1 switch and a brown faceplate (as opposed to the later chrome faceplates).
This preamp is a high quality product that was lauded for its clean channel by Guitar Player some 20 years ago. It features 3 discrete channels switchable from the front panel or from the accompanying footswitch. The clean channel has a Fender blackface topology with reduced bass end to match the other channels (it still has plenty enough) and remains clean even with high gain settings. The "Mean" channel is a slightly modified Marshall 2203 preamp, and the "Scream" channel is a heavily modified 2203 version (think Bogner type). The 3+1 switch reconfigures this last channel by inserting the clean channel at the beginning of the signal chain.
The Mean channel is very good for overdriven rythm work, with good dynamics and sustain but may not be fat enough for some tastes. I modified mine back to 2203 specs and it sounds like a high quality version of its inspiration: the highs are less harsh and the notes definition is very good. That could be due to the high quality components. the Scream channel goes very far in terms of saturation. It definetly shreds and is primarily aimed at lead work with strong mids and moderate bass end. In its 3+1 mode, it has a bit less gain, more dynamics and a more "vintage" or "Fendery" flavour. This mode can pretty much do it all, from pop to rock, to metal. It is one of my favorite tones from this preamp. In fact just talking about it makes me want to play it!
The Trio's effects loop is a passive resistance network. It doesn't offer the versatility of an active loop. but it doesn't alter the fantastic tones that this preamp offers.

