OK folks, I ran my bypass tests with:
Bass into a single channel on the DL1608
Aux channel5 into B3n into computer interface right
Aux channel6 into a bypass looper into computer interface left
I had the looper in the mix so that I could have identical cables for both signal paths.
I then adjusted levels at the computer interface until the levels looked identical.
Well, it seemed to work quite well. I recorded slap and fingerstyle. I never got to pick playing because listening back on headphones or my monitors, the differences were minimal to point of being insignificant. I could not have picked them out in a blind test. Wow, OK.
I then took the cables that went into the computer interface, and plugged one at a time into my amp, listening through the Big Twin II (a VERY accurate and flat response speaker). I had two identical cables in my hand, so I flipped them around and randomly plugged one and then the other in. Interestingly I could hear a difference in the "body" of the low end through the amp, and I could readily distinguish one from the other as I shuffled the cord around and plugged it in. But the difference was very subtle, and this is with me sitting directly in front of the most accurate and revealing bass speaker I've ever heard.
So, I'm not going to put up samples, because I don't think anybody would reliably hear differences (I listened on my HR824 monitors as well as decent Audio-Technica headphones and couldn't hear differences). There is of course a lag in the signal, I didn't measure how much. It's not a lot, but it's enough to cause nasty phase issues if you try and use an external blend, so I definitely wouldn't do that. The two signals played back together had that out-of-phase hollowness, but not enough so that I could hear it as a delay or slapback. That delay could perhaps account for the perception of the attack being less immediate, since the player can feel that delay although the listener cannot.
So in a clinical situation (bypassing with identical cables etc., I'm satisfied that there is not enough tone suck to be audible. What worries me a bit is that I really did hear differences when swapping cables so I wonder if the real-world results might be more audible. But just a bit.
I have to say, I'm happy to be kind-of-proved wrong, in that it appears that given the right cable and impedence situation, the tone suck is minimal (or at least it's less than the difference between brands of cables).
So I'm going to try to take this bad boy out on my next gig. On my big-boy pedalboard, the main always-on effects are a B7K Ultra and a Origin FX Compact Bass compressor. From my listening, the B7K simulation in the B3n gets the essential character of the real thing very nicely. It would be great if the blend and drive is accurate also, tomorrow I'll test that out. The compressor situation however... The Origin CB is crazy good, and I can compress my signal hard to even out the playing while also making it more aggressive and attack-y, but it still sounds almost completely unprocessed. I doubt I'll find something like that in the B3n, but a boy can dream...
TL;DR - B3n is good. Choose your cables and impedence match carefully.
