I have the Sennheiser HD-600, the Grado SR-225 (I currently have them with Senn 414 pads which are by far the most comfortable and best sounding pads I‘ve heard yet on a Grado. The Brillo Bowls they come with just suck and are really uncomfortable.
I also have, have had and have extensively listened to other headphones from Grado like the SR-325 and 80’s the AKG 240, 501, 701’s, Beyer 880’s and Sennheiser 650, 580, 25 and others I’m forgetting about I’m sure.
I find the Grado’s in general to be very aggressive and bright but not all models. The 225’s and RS-1 are the least bright and still can be fatiguing. They always lack weight in the bass and midbass and basically have no soul. I still have them and I like them but mostly for Rock and Classical music. Oh and for my iPod which can actually drive them but man does the Grado let you know how bad an iPod actually sounds. Sometimes it’s downright awful.
The Senn 600/650 are not rolled off or bloated to my ears and to most people’s ears. If your hearing is rolled off as MANY people, especially over 50, is you might find the 600’s rolled off compared to a Grado 225. Hell, a 225 is rolled off compared to the 325 or a 80 for that matter. So keep in mind that this is the norm and that they are two distinctive sounds for very different ears. The Sennheisers DO have a very full and rich bass, they likely have more bass then most headphones which is still not half what my speakers have so put that in perspective. – yes MOST headphones have too little bass, it’s a problem and were all aware of it. The Sennheiser also image very well and the open air sound they have is pleasant. To say they are polite is likely true but I like polite especially when the speakers are a ¼ inch from my ears.
I also like (and will likely buy) a pair of AKG 701’s. They are really great, a little brighter then the 600/650’s with less bass and a slightly larger soundstage.
The Beyer 880’s are VERY similar to the 600’s but I always feel like the 600’s are just a touch better all around. Tighter focus and bass. I even heard a pair with an upgraded cable that helped, gave them more bass and mids but still the 600/650’s were my choice.
A buddy just went through three SinglePower amps and he finally settled on a MPX3 with the giant PSU and Black Gates, silver point to point wiring and some choice NOS tubes. This headphone amp is just absolutely superb! Anything you play through it sounds great, its amazing. It was voiced with the HD-600’s because the designer loves them. My SR-225’s never sounded as good. My Van Alstine T7 preamp is good but doesn’t compare to the Single Power MPX3. The T7 is somewhat analytical and just a little plain or lacks excitement. No robust bass or lush midrange vocals, no giant soundstage and sparkle but it is very transparent and neutral and can easily drive any headphone I play through it. I’ve tried a few other amps for my headphones and it fairs quite well to most.
The T7 is a big bang for the buck preamp and it’s hard to replace without spending lots more or compromising and doing without. I’d consider the new Ultra or T8 but loaded the way I want it, it’s over $2300 and the doors start opening wide, especially in the used audio HiFi market. But remember that the SinglePower MPX3 I described briefly above is about $2000 and its JUST an integrated headphone amp.
The only problem with my T7 SLR is that with nearly all the RCA jacks filled, the preamp is being lifted up in the front by the weight of the cables and I have relatively small and light cables. I wish the darn preamp had a 10 lb plate in the bottom or something to weight it down.
I should post some photos; it’s really funny in a not so funny way.