Headphones - Senn HD 800 or Grado RS1i.......

I use a pair of Black Treasures (from Ian) in my Modwright Transporter. I agree, they are excellent tubes (in that application at least). Sorry, I don't know what you are using them for though - which tube type are you using? The only competitor in the Transporter that I have are Tung Sol rounds, which are also excellent, but mighty expensive and getting more and more difficult to find.

I am using the Shuguang black bottle 300b's in my Cary.
Not sure if they make any tubes you would need for your
Woo amp. It would be worth trying out if they do.
I only have about 150 hours on them and they have been
a joy to listen to. They say that 300 hours are required
to brake them in so I am not sure how much better they will
be at the 300 mark.

I will have to do some research to see who carries these
cans here in Seattle. Unfortunately, this month is extremely
busy for me so it may take me a while.

Just an update on the Grado PS1000's. I spoke to a dealer
here in Seattle and they are on back order due to QC problems.
Sounds like it will be at least several weeks before they come
in. I am curious as what the QC problem is all about.

As for the Senns HD 800s, has anyone tried different cables
to tip down the treble and maybe add some musical warmth?

The Sennheisers have possibly the best soundstage of any headphone I have ever heard. As far as a cable, there are a few main brands to check out -- ALO Audio, Apuresound, Stefanaudioart, and (my personal favorite - especially with their complement cable) doublehelix. As far as warmth you'd want a copper cable instead of silver. The whole subject of headphone recables is a sore subject to many, with half the people proving theres no difference through blind tests, the other side proving the opposite with the same methodology. The truth is, if theres warmth issues even with your cary, I don't think these are the cans for you. The Audeze LCD-2 are currently as close to a consensus as the head-fi world can get at best all arounders in production, and are specifically noted for having more warmth and slightly rolled off treble compared to the hd800. At $950, they're also cheaper.

My recent search for headphones ended with a short list of two - the Senn HD800 and the Beyerdynamic T1. Both are outstanding headphones in their own right, but to me the difference between them came down to their musicality.

I found the HD800 to be more analytical - I found myself listening to recordings and being impressed with how good a recording sounded. With the T1's I found myself getting drawn into the musiccal experience and lost in the music. I have not regretted buying the T1.

If you are looking at high-end Senns or Grado, you owe it to yourself to compare them to the Beyerdynamic T1 as well.