The truth is, I can't hear it too loud because my neighbor is an asshole. Volume scale vol.: 0-98 (dB.:-79 - +18).The DRA is rated 100 W 8 ohm, 120 W 6 ohm but at higher THD. It is only 4 ohm compatible if you use the 4 ohm impedance setting. If you use that setting, the output will be limited, likely to well below 100 W. If you leave the setting at 8 ohm, it will likely give you the 140-150 w that you seem to be expecting, based on bench test results, but at that output level, it can't sustain for too long.
So, it is up to you to accept certain risk. If you don't listen loud, such as at 10 dB or more below reference level, you may be fine, just not something I can recommend. It is better to get a real 4 ohm rated power amp.
So usually vol.40(-40dB).
Sometimes vol.50(-30dB)
Very rarely and for a short time vol.60(-20dB)
I once tried vol.80 (0dB) for a few seconds, it's very, very loud and it's not even full volume, so maybe I'll never listen to it at full volume. I don't know how many watts that was, or how many dB, but if the DRA800 can send 100W RMS to 4Ω JBL subwoofers with a 6Ω or 8Ω setting without a problem, I'll be happy. I think that's more than enough.