I've been gigging with my d800 for a few months now and I couldn't be happier with my bass sound. I have tried almost everything under the sun, and although I know the majority of your tone is from your hands, I do appreciate that certain amps can contribute meaningfully to your sound.
Previous to the D800 I had a Traynor YBA300 all tube amp. It was a beast, nothing compared to the weight of an SVT, but all the wallop, tone and volume of one! I loved it, but soon it started humming (I bought it used) and I was starting to tire of the 50 pounds the head weighed. I had been using Genz Benz and Markbass earlier, and was starting to feel spoiled by those 5lb heads, but I always felt I was missing the girth and tone that only tubes seem to bring.
I went to a local music store intent on buying the subway preamp to girth up my markbass F1 that was just too clean for my liking. that combination was excellent, lots of meat added instantly to my tone... however, just as I was going up to the register to pay, I noticed a used subway D800 sitting for $650 CAD with it's shoulder bag included. I A/B'd the D800 against the markbass F1 and subway DI combination. Honestly, the sound was very similar, as the Subway DI adds a lot of tone shaping, and has that (what I describe as) mesa subway 'tube crunch' to the tone when you dig in (as I do) when playing expressively.
For under twice the price of the subway DI, I would have a louder amp, 2 ohm option for added cabinets, carrying case, AND I would have it all in one package instead of two (amp + DI pedal). It was a NO BRAINER! Walked out with it!
I played it through the matching subway speakers, and I may eventually grab a couple (or few), but right now I am content running the D800 through a Traynor TC210 x 2 vertical stack, which has headroom for days and puts the punchy bass tone near ear level, or with my Bergantino HT112 and EX112 stack, which is more rich in mids. If needed (which I haven't yet) I can run both 12's and both 210's for a massive setup... but I'm not playing stadium stages these days...
Tone wise, the subway does start out a bit dark, as some of mesa bass amps can sound. But, there are a lot of tone shaping options, from the four band EQ (bass, low-mid, high-mid, treble) and the 'Voicing' knob which goes from flat to added mid-scoop, bass/treble boost... and a couple contours in between.
I find if I plug in my bass, set the gain about halfway, master at 9 o'clock to start, EQ and voicing flat, then roll in the voicing from left (0) to right (full) until I find a sweet spot that I like, and then flavour with the EQ – VERY minimal adjustments!
There is also a 'deep' switch, that when engaged will immediately force a smile, but live I find it is not necessary, as we go through PA for subs, so no sense punishing my speakers with extended lows that may mess with the others on stage. I did use it for an outdoor gig and it made my bass sound very full on stage.
The DI on this amp is great, and although I used to ALWAYS run my DI's PRE EQ, I actually run mine POST EQ/Preamp to get the tone benefits. I have never had a soundman complain... I also rarely make any adjustments to the preamp or EQ after soundcheck... and always get compliments on my tone. I play primarily a Stingray5, a squier VM Jazz 5, and a Warwick German Thumb5 NT.
I actually don't gas for other amps... sometime when I do think about getting a tube amp again, I just crank the gain on my subway (when practicing at home NOT at a gig) and hear the added lush warmth added to my tone.
I am am one happy customer... you may be too
Mesa Boogie Subway D800
MESA BOOGIE SUBWAY D800 Designed & Handcrafted in Petaluma, California Class D Power with 8/4 or 2 Ohm Impedance Switch for optimum Power to Load