Like many of you, I was wandering how would Crack work with low impedance headophones like Grado, Alessandro.
What a suprize! It rocks with my Alessandro Music Two 32R headphone!
Nothing falls short compare to the HD650.
Just different flavor due to two different headphones' native sound sinature.
Knowing the Crack would not be ideal for the Music Two due to its 32R impedance, I was originally building the Crack w/ Speedball for my son's HD650.
I was very suprised that it sounds great and I don't feel any comprise at all.
I like it so much I might build another one for my Music Two.
My main headphone is a Stax 507.
The Crack+ Music Two won't be shy against the higher dollar Stax 507.
The Music Two + Crack is detailed, transparent and good bass.
The tube amp gives less glare and fatiuge compard to the SS amp I used.
I up graded the volume pod to a step attenuator later.
Everything gets better. More detailed, transparant, better band width...
However, with the Music Two, keep the stock pod is also a good option.
The stock pod is warmer, less fatigue while still remaining sufficient detail.
It is more relax and very musical.
I might keep it stock for Music Two.
Music is less in-your-face and is better for playing music while reading.
My 2 cents. FYI.
YMMV.