The PS-1's bass is not "overpowering", but it is certainly pronounced.
Most head-fi members seem to agree that it is
system synergy, which lies at the center of the art of putting together a great headphone system. It seems that headphones like the Sony R10 require a lot of effort in terms of system matching,
inter alia due to its perceived bass weakness (hearsay). The efforts range from rolling rare vintage NOS tubes (head-fi member Hirsch) to having giant custom two-box amplifiers handmade for it (head-fi member Nik).
Getting the best out of the PS-1 requires some attention to detail, too. It's that easy. And that's all there is to it. Some amp/headphone combinations are better than others, and certain combinations may result in a sound that's disappointing, even if the components enjoy an excellent reputation on a stand-alone basis. It's very simple. Give the PS-1 the same credit that you would give the R10. Actually I am not sure if
that much credit is required in the first place -- I find the PS-1 quite easy to handle, although it
is a little amp-dependent. Combine the PS-1's with an amp that does not have a pronounced bass, and there you are!
Just like head-fi member Hirsch, who used to be very happy with his HP-1000/EAR HP4 combination (after some tuberolling), I think that the PS-1 sounds excellent driven by the EAR HP4. The bass is deep and there's a lot of it, but it's never overpowering. I also enjoy the PS-1's sound out of the audiovalve RKV II
without the Impedanzer, but due to the impedance mismatch, there is a little background hiss, which I am willing to tolerate, but keeps me from recommending that combination to everone else. The PS-1 is even a very good match with the Larocco Pocket Reference, but obviously you have to keep the bass boost turned "off".
Coming back to the thread starter's question: The difference between the RS-1 and the PS-1 (apart from the obvious choice of material -- aluminium instead of mahogany) is that the PS-1 uses better drivers. I do not know exactly what that difference is in technical terms, but was told by the German distributor (who claims to be the mastermind behind the PS-1's development) that the PS-1's drivers are "an improved version" of the RS-1's drivers. In fact, the distributor told me that the PS-1's drivers are those that were initially developed by Grado for the "FS-1" headphones belonging to the ultra-expensive wireless "Freesystems/Grado" system. As a matter of fact, the PS-1 looks very much like the FS-1, with the main difference being a different combination of the colors black and silver on the grilles and the circular thingies that hold the earcups.
I like the sound of the PS-1 sooo much more than that of the RS-1 that I could not wait to sell the latter. The PS-1 is the best sounding Grado I have ever tried, but obviously I haven't tried them all. Saying that the decision between the two headphones is a matter of taste is a truism, because that always applies. Unlike others, however, I can't say that the sound of the two models is
very similar, apart from the obvious similarity that results from the "Grado house sound".
The main weakness of the RS-1 has been mentioned before: It's the "sssss" sounds that get screwed up big time. Or listen to a steel-strung acoustic guitar with the RS-1 -- the high strings (e and b) just don't sound right; not clean, almost distorted. The thing is unable to handle quick and strong treble impulses. And
that cannot be cured with a different/better amp. The midrange may sound OK on the RS-1, but the PS-1's bass is so glorious that the RS-1 simply can't match it. And that's only the pseudo-scientific/analytical way of looking at it. The PS-1 is also a fun headphone to listen to, much more so than the RS-1.
As I posted already on
December 16, 2003: "Out of the box the PS-1's sound is much better than that of my run-in RS-1s; these two models are playing in two completely different leagues, as far as I'm concerned. As of now I must say that the PS-1s are much more fun and also more pleasant to listen to than the RS-1s. Really, really nice. Very nice indeed. I am looking forward to getting to know these headphones."
A little later I posted
this (and more): "I have always perceived the RS-1's sound as slightly distorted, as less "pure", less "clean", more "grainy" and therefore less elegant than the top-of-the-line Sennheiser headphones in conjunction with ZU Mobius cable."
"Now I can describe a little better why the PS-1s sound so "right": As mentioned before, I perceive the PS-1's sound as purer, clearer and less "distorted" than that of the RS-1s. The bass appears to go deeper, and in any event it is much better defined, really powerful and not boomy at all. The midrange is pleasant, but not laid back in any way. Really up-close and informative, as a matter of fact. Some would say, typical Grado-sound, just in its best incarnation."
"The nicest surprise to me is the PS-1's treble. It is so much clearer and better sounding that I became even more aware of the characteristics that I dislike about the RS-1s. While the latter headphones add a slightly scratchy and distorted quality to all kinds of treble-heavy and explosive sounds, from triangles and cymbals and snaredrums to "s" and "t" sounds of (female) singers, the PS-1s reproduce such sounds with an ease and effortless transparency that takes less than five seconds to notice. It's even possible to enjoy classical music with the PS-1s!"
Following is an excerpt of my impressions
after some days of "burn-in": "Over the weekend the PS-1s have "opened up" very nicely, which means that their sound (which was already more than satisfactory right out of the box [...]) became more "airy" in the midrange and the high end. Classical music is surprisingly pleasant to listen to with these headphones; I am thinking in particular about an extremely well-recorded cembalo piece that I also enjoy very much via my room speakers."
"The two big advantages of the PS-1 Pros are the stability and the clarity of the sound. As I noted early on, the bass is deep, well defined and not boomy at all. As the German reviewer pointed out correctly, that characteristic provides the
sine qua non for the development of a "liberated" and transparent sound, which is based on that foundation. The thing is -- you really want to hear what the PS-1 Pros have to tell you; I for one care much less for the RS-1's message; the latter are outclassed by the PS-1 Pros."
The conclusion is therefore: If you like the RS-1, you'll love the PS-1. If you have a principal problem with the Grado house sound, the PS-1 ain't gonna solve it. So much for now.