Sonic Defender
Headphoneus Supremus
I hope the treble spike doesn't bother you like with the TH-600, and can't wait to hear what you think about the 339/600 combo.
There were a few times already where I could tell it was a little spiked in places, but it didn't seem to bother me, but maybe over time it might. If so I would likely just EQ the spike down a hair and hope that works. As well, because like you I listen to more than one headphone I tend to spread the listening sessions out so that also limits how much exposure to the spike I will have.