The Rocktron Piranha is the gain king among the '90s tube rack preamp.
Compared to the most famous A/DA Mp-1 , Marshall JMP-1 and Mesa Boogie Triaxis, it was more similar to "modern gear" than them.
First of all, his base EQ is kinda "Flat / HiFi", so you need to use the Bass-Mid and Treble Eq way more than you usally do on a tube preamp/amp. It has Active EQ.
It also features a parametric mid-frequency knob; you can choose which frequency the Mid knob will affect, from 250 Hz to 7 kHz.
It as an integrated Hush Noise Gate, one of the best in the 90-2000 and still very good today.
Last but not least, it feature an Input gain/trip knob, to allow input level adjustment when switching between guitars which provide different output levels. Something Tonex users will kill to have ! =^.^=
Here a pic of the inside, while i was doing mantainance and tube swap.
Atm is running with 2 EVH 12AX7.
The most famous artists who have used Piranha (as far as I know) are: Slipknot, Judas Priest, Nightwish, and Gary Hoey. Probably many more.