I just installed a Schiit Loki EQ device that sells for only 149 from the Schiit website. It has four knobs that have a decent click at dead center and are turned left or right to influence the EQ. Each of the four knobs controls a different EQ range, rather than just the old “bass/treble”. It is passive, and has a bypass switch to take it off line if desired. It gets VERY HIGH reviews by users as not molesting the quality of the signal. I can not determine any negative impacts to soundstage or quality of sound. Each knob adjust at a very slight EQ level for the first portion of the turn, then gets more aggressive as you turn it more, allowing for very fine tuning. You simply install in the signal path between your pre and power amp. This is not the old EQ design, it has the mastery of the latest technology that Schiit has become well known for, at a very good price. I too have a tube pre-amp, but with no EQ controls, I previously did not like any of this in my system. Im 65 yrs old and have been running tube equipment since I was 15. This is the first EQ i have allowed into my system, usually run everthing flat and straight. Its that good to my ears, and saves me a little money by not always rolling tubes to get the sound I am looking for. I now get to adjust it for every source and quality of EQ recordings to my taste. I usually don’t influence it much, but just enough to fine tune each source or specific music. Read the reviews on the Schiit website or on-line idependant reviews. Don’t like it? Send it back. But I don’t think you will, its that good.