Hi, 
I'd like to draw on your experience and ask for your thoughts on my plan to put together a pedalboard for practising at home and playing along with MP3s, entirely through headphones. I suspect it may be overkill, but I want to get the best possible sound out of my Alembics and other high-end basses. May I please ask for your opinions or advice? Many thanks! I like the Aguilar AG as much as I do the Genzler Magallan preamp/DI. I am not into cab-sim and adding too much grit.

Bass
↓
Peterson StroboStomp Mini
↓
Cali76 Bass Compressor V2
↓
Sushi Box Finally V3
↓
Aguilar AG Preamp
↓
Neunaber Immerse MkII
↓ stereo from here
KMA Stereo Headphone Amp

I'm using the Magellan pre with the switchable contours (A=modern hi-fi-y, B=Ampeg territory), a sweepable mid control and usable bass and treble, plus the adjustable high-pass that comes in handy, into the fx return of an old SWR WM12 combo. It already has an aux in for play-along (makes it mono) and a proper headphones out.

Mind you, I'm not using the B contour or the aux in, or a compressor, or any fx.

I'm convinced that the Genzler is a great amp. I still have my old Shuttles. The aux on the Magellan pre take TRS plugs but the headphones are mono per design, so any music that is played in stereo thru the aux is indeed mono on the headphone output. I like tubes but not the distortion that aften comes with it. That's why I was thinking of placing the Sushibox before the actual preamp, either Aguilar or Genzler. The Sushibox has a variable HPF. I also use Glockenklang and although it's a very musical amp, it sounds a bit sterile, to my ears at least. Thanks for your feedback Adriaan!

I followed your suggestion and will opt for the Magellan. I ditched the compressor.