Turn up the gain on that pre amp. Turn it up until you see that red light flicker, then you will have a lot more travel on your master. Ampeg pre amps need that pre gain up to get real output. That is part of why the SVT-3pro is considered underpowered, no one wanted to run the pre hot enough. Another thing to consider is the response of the cab and the pre amps used. The Dually doesnt have any massive spikes. The K140's do, so your ear hears that spike and goes, "FUQ this is loud" Put them on a meter measuring output at 80 hz, and it will be a different story. The EQ on the pre amp can help all that, but it is actually more difficult than it sounds to balance two different eq's, let alone the rest of the signal chain.
Good eye.
Getting used to the VTRM gain settings took me a bit. Settled on the SVT "like" settings w a little EQ tweaks I can't open it up much more than quarter throttle on the master. I was choking back the amp to see if the tone would chage with with the master opened up some. Didn't so much.
I'd still like to get my hands on a Trace Elliott GP12SMX pre. One day... One day...
Any of you guys have experience with EMG 45P pickups? I'm never using my Drake Custom lately because the Nordstrand DC pickups just don't really get me to my tone of preference. It's routed for 35 size pickups, so that's about the only option I can think of to get there. I really wish I had just gotten it built with a P or a PJ, at the time I figured if I was going custom I should try something different and it was a nice though in theory. It's making me consider selling the bass, which breaks my heart because it's the nicest instrument I own or have owned. In a perfect world I would keep it and have Andrew make me another with my preferred pickups or at worst sell it and then do that, but there's no way in hell that's happening in my current financial situation.
Keep your bass man. If the EMG will fit the cavity give that a try. It's not going to be 100% Passive Pbass but may swing the options to your favor. Wire it up 18V and chooch.