As an aside, I've had various Amplifi's (and still have the TT as it's very versatile unit and can bluetooth music etc to it), plus had HD500 and HD Pro X but the Helix Rack is SIGNIFICANTLY better. I mean it's unfair to even start to compare as the Helix (especially with the new 3.0 firmware) is RIDICULOUSLY better. My advice, find a workaround as the benefits of the Helix blow the HDs out of the water! Seriously, get one!