Fun Adaptations to Hi Fi

i'd be happy to attach here links, but you'd be better served (as there's a wealth of info, reviews, gear slutz forum, etc.) simply googling "charter oak peq1".  check it all out. 

now I use it EVEN IF THERE IS NO EQ WANTED, as with all the dials on flat, it actually improves soundstaging as compared with without it. I it is also DEAD SILENT noise floor...

well, it's interesting indeed.  I many times have set the thing on flat and cut it in and out, using different types of music all of which was very well recorded.  I made sure to pay no attention to tonal balance and only attention to musical images, eg how well shaped out they were, leading edges to vocals and instruments, as well as clarity of transients and decay of cymbals, eg with jazz.  to my ear, nothing is lost and often a subtle improvement seems present.  but since this is designed as a broad Q mastering EQ for the studio, the real question is as follows:  can putting a high quality high fidelity PRODUCTION box in the signal chain defy the old adage you referenced that the less boxes in the chain, the better the SQ.  after all, every post-mastered recording we hear on our high end equipment had several boxes involved from mic to mixer to mastering.

food for thought!  all I know is that what I hear coming from this setup is highly musical, highly hifi, and quite fun to play with.  it's like magic sauce.  it seems to me in all my listenings over the years to be the best way to approximate a $100,000 system with only about 10-12 grand invested.  it really does give the great gear a run for the money.

...is that every extra device in the signal path is detrimental to the sound.

I have been of similar understanding, but I would say "...is that every extra device in the signal path is influencing/changing the sound" rather than being detrimental to it.

In such a case, it is almost expected that the device OP is mentioning gives her/him results he experienced and liked even when set to "flat". It is probably influencing the sound and it is probably in the direction he likes. After all, that is what that particular component was designed/invented for. To change the sound, not to leave it untouched.

One thing that many people on these forums rarely mention is about tweaks etc. It comes across as if tweaks are always for better which is hard to believe.

To answer the question, I do have a tape loop, but am not using it and have no real interest in adding EQ somewhere there. Primarily because that would mean more work. I am fine with just bass/treble which I barely use anyway. Loudness button is something else. It is a darling.