Sennheiser makes headphones with headsets, but they aren't comparable to their standalone headphones. Give me a second......
d@mn 56K.....
Link.
These
do not have sound quality comparable to the dedicated Senn cans.
Grado and Sens are on about the same level.
I wouldn't say that. Most people compare sets like the HD497s to the Grado 80s or 125s, all of them fine for what they are, but they are all low end(for audiophile gear standards). When you step up to the 600 series Senns I think they really pull away, as long as you have an amp of course

For the lower end, and arguably the mid range, the Grado's do sound pretty good, but as mentioned they are not close to the comfort level of the Sennheisers.
All the talk about Zalmans, Platronics or the like- they are complete junk in comparison to what we are talking about. Be aware though, that the 'low end' headphones looking at Grados and Sennheiser
start around $100 and go up from there. A 500 series Senn will run you about $200(amp helps, but not required) with the 600 series pushing around $300(and requiring an amp for ~$100 more to drive them properly- they sound very muddy in comparison without one, although still worlds better then the regular consumer gear).