OK - thank you to everyone who contributed and helped me sort out what I"m hearing.
To sum up: The issue seems to be with the headphone output on the 2i2 and is not a "tone suck" of the 2i2.
I took the advice of many (@PJsaure, @dkelley,
@Geddy Claypool, etc.) and ran a DI out from my Darkglass into the 2i2 and recorded into Garageband using the "Clean Bass - HiFi DI" configuration, with no eq and no plugins. I made 3 recordings - one with the DI out to the 2i2 and NO cab sim, a second one with the DI out WITH a cab sim, and a third recording going 1/4" out of the Darkglass Vintage Ultra v2 into the 2i2 with no cab sim - same settings on the DAW.
I used my regular bass - a Yamaha RBXJM2 for all the tracks.
The DI out without any cab sim is the closest to what I hear when I plug my headphones directly into the Darkglass unit. It's not perfect but it's close (number 1).
The DI out with cab sim sounds the worst in my opinion - too much woolly fuzziness and lack of clarity (number 2).
The 1/4" out into the 2i2 sounded more like the DI, but didn't have the same fuller tone that the DI without cab sim provided (number 3).
Here are my results:
1) Darkglass Vintage Ultra v2 DI WITHOUT any cab sims into the 2i2 then USB connection into my iMac with Garageband's "Clean Bass - HiFi DI," no additional eq and no plugins:
[Invalid or Expired Link Removed]
2) Darkglass Vintage Ultra v2 DI WITH default cab sim into the 2i2 then Garagband (same settings as above):
[Invalid or Expired Link Removed]
3) The Darkglass Vintage Ultra v2 quarter inch out WITHOUT cab sims into my 2i2 then Garageband (same settings as above):
[Invalid or Expired Link Removed]
IMO, the DI out without cab sim sounds best and is closest to the sound I get when I plug my headphones (AKG K240) into the Darkglass headphone out jack. It's not perfect, but it's close.
The 1/4" sounds closest after that, and the DI with cab sim sounds the least like it.
All in all, NONE of my recordings - DI or 1/4", cab sim or not - sounds anything like the headphone with direct monitor on the 2i2 - which is just thin and gutless.
In conclusion, I feel the issue is with the headphone output on the 2i2, and not a problem with the whole system I will be using a DI out thing to the 2i2 from now on.
THANK YOU everyone for your help and great ideas!
Stay loooooowwwwwwww.....