Interestingly, I used to own Bose 901's back in the late 1980's. This was long before I had any skills in applying PEQ to tame FR and, of course, long before automated room correction. I loved those speakers!
True, if your PEQ is applied using the HTP-1's PEQ capabilities, it will affect headroom. Just curious, are you running Dirac Live calibration after applying PEQ, and how do the 901's sound with Dirac?
I tried both, running PEQ before Dirac (to allow me to run Dirac off) and after and running pure Dirac. When I manually PEQ and do not run Dirac, the center image is tighter. So, if I really want to listen to music solo on that system, it’s Dirac off, turn on PEQ.
Running pure Dirac works better for headroom, and it corrects pretty well except for the region above 14 kHz. With the Storm Audio room target, it’s fine. With a Harman target, Dirac is too cautious about correcting the treble.
My home theater is unique in that the focus is great sound everywhere, reference sound nowhere. That’s not how most hobbyists like their setup. (I have my office setup for the clean reference sound where I will use the Meyer Amie and previously had the JBL 708P.)
Home theater room is disproportionally wide and the rear speakers are immediately behind a large sectional sofa. It fits 8 adults comfortably in a single row about 13 feet from the display. I have Bose 901’s as L, R, and rear L, R. I then have a pair of JBL S/2600 flanking the screen as dual centers. These have asymmetrical horns so you maintain a center image even entirely off axis and keep the voice at screen height rather than below screen height. It’s weird, and it shouldn’t work due to comb filtering and the woofers not being angled — but it works great in practice. The center is basically dual 12” woofers and 92 dB/2.83V so dynamics are there. Front height direct and rear upfiring have the added HRTF curve which does enhance the perceived height to my ears in my room.
NOT my photo, but it gives you a sense of size of those JBLs.
I am looking forward to Dirac ART because it should really take advantage of the dual 12” woofers in my center channel and the “equivalent” 13-4” woofers of each Bose 901 distributed evenly across the room.
My subs are JL Audio F110 and Velodyne DD10.