Yeah, I'm on a waitlist for a review set of the Tungsten. Ryan is quite busy trying to keep up with orders.
Well, there's nothing wrong with the Piety other than not having the widest stage I've heard. It has remarkably good synergy with ZMF headphones, of which I own most of them. It's our go to recommended amp on a budget for ZMFs in the
ZMF amp thread.
Bassy, warm, available currently that doesn't cost a fortune? Perhaps the Meze 99 classics or Campfire Cascade. Whether or not you will enjoy those more than your current setup, that's nearly impossible to say. So much of this hobby is based upon personal preferences and system synergy. Personally I found both to be too bassy for my tastes, but if forced to pick between the two, I'd go with the cheaper Meze 99s. The bass on both are so dominant that the mids tend to get stepped upon, but much moreso on the Cascade.
If you want to get a nice warm sounding amp that can drive most any headphone on the planet and not have to worry about buzzing, I'd look into Violectric amps, and if those are too pricey then I'd suggest amps made by Lake People. Violectric, Lake People and Niimbus amps are all the same company. Lake People is their entry level gear, Violectric middle ground and Niimbus are their high end amps.
My v550 pro has adjustable gain keys in the rear, so you can adust how much power is coming into the headphone at any given time. For example if driving the Susvara you'd set the gain to +24. If you swap to a 32 ohm 104 sensitivity headphone you'd pickup a ton of hum @ +24, so you drop the gain down to zero, or even minus 6 and then you'd have no more hum. Gain is a totally different function from the volume knob.