Just about the exact setup I've used for the past year except I have the HD600's. I think you will really like the combination, I know I did!
Just about the exact setup I've used for the past year except I have the HD600's. I think you will really like the combination, I know I did!
If it helps I just bought a Mk IV (whilst in China so no shipping issues) and use it with my HD600's and so far I am very impressed. Walking around smiling even though I am back at work!!
What tubes did you substitute? I am thinking of doing the same thing but am not sure which ones to get and have no desire to have a stock of unused tubes around the place.
My favorite so far is the GE JAN5654W. The GE tube has nice clarity and a more exciting sound which pairs nicely with the sennheisers. The mullard M8100/CV4010 is my second favorite and tons of people love it. I like the mullard as well but to me it isn't as exciting as the GE tube but is a nice full body sound. It can seem a bit too smooth sometimes for me depending on the music with the HD650. Its a love hate thing with the Mullard but the GE tube always sounds good to me.

My favorite so far is the GE JAN5654W. The GE tube has nice clarity and a more exciting sound which pairs nicely with the sennheisers. The mullard M8100/CV4010 is my second favorite and tons of people love it. I like the mullard as well but to me it isn't as exciting as the GE tube but is a nice full body sound. It can seem a bit too smooth sometimes for me depending on the music with the HD650. Its a love hate thing with the Mullard but the GE tube always sounds good to me.
Thanks, that is very helpful. I will have to start experimenting!
I forgot to mention this thread before. It's full of impressions for different tubes.
http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide