No plans for a new headphone amp at the moment. We are working on other products and I am personally working on a few other non-kit things as well. Thanks for all the kind words. I try to develop a product with at least a ten year lifespan. We don't always get there. That said, we don't have any plans to update or retire the Mainline any time soon.
I was listening to some pro setups while in the Bay Area this past week (along with playing with Goggle earth on an Oculus rig - WOW!). Tubes vs. SS, analog vs. digital, horns/panels/dynamics, and speakers vs. headphones for that matter, are from a certain perspective not as relevant as the simple idea that some listeners want a fuller more mellow sound and some want a more resolving and detailed sound. Interestingly both camps want smooth treble, punchy bass, and coherent imaging. I think there is a lot of that going on in the differences between our various headphone amps. Crack is in the warm and mellow camp, Mainline is in the resolving and neutral camp (as is the Neo), S.E.X. falls perhaps in the middle.
