This Regent 150 from Fredric Effects definitely falls into the category of the 'always on' pedal. It adds a natural fullness / glassy treble (depending on settings) which you miss when it's switched off! This is not a pedal of drama but has the power to add a subtle solidity to the signal chain.
Here is what Fredric Effects say...
'The Fredric Effects Regent 150 Preamp is an accurate recreation of an obscure East German preamp, using a charge pump to match the voltage of the original ampifier and real NOS 40 year old East German transistors.
The Regent 150 Preamp uses the preamplifier and EQ circuit from the Vermona* Regent 150K amplifier of the 1970s, a staple of Eastern bloc rehearsal studios, stages and bedrooms. When first prototyping this circuit I'd expected an interesting lo-fi curio, something punky, scrappy or perhaps thin sounding, however the result has far surpassed expectations. The treble control adds a clean sound which is glassy and precise, and the boosted bass is warm without being flubby. Overall the effect also adds a little welcome compression. Use it as an EQ, boost, or just leave it on all the time because it sounds so good.
*Vermona is a trademark of HDB electronic GmbH'