Some comments from Spain...
On one side, I have been using the SRS-001 for some time already, fed from a 5v power supply, without any problem. The sound is much more robust than with batteries - and lasts more. I have been using it for my business trips, fed from Macbook -> iTunes -> Audirvana -> Meridian Explorer -> SRS-001. I carry as well an Ultimate Ears UE10 (custom earplugs), which in late 2005 was the top of the brand, but I prefer the Stax for extended listening and much wider soundstage. However, it has always been a compromise, since it has a limited treble and low bass.
It took its good 50 hours to start sounding well - the frequency extension at the beginning was much poorer - one could think that the machine was broken.
My preferred way of using it is listening to it while I work or read on the computer, typically in the hotel room. I don't use it off an iPod - I prefer the simplicity of the UE10.
Lately I have received an SRS-005 Mk2. For the way I was using the SRS-001, I much prefer to have a proper amplifier like the SRS-252s, and having the compatibility with other energizers I have.
With the breaking in experience of the SRS-001, I had to be patient with the SRS-005. Surprisingly, the part that took longer to "open up" was the amplifier. I was comparing both parts with different energizers (SRD-X Professional, SRD-7 Professional and Woo Wee) and different earphones (Lambda Professional and 404 Signature), and there were some clear conclusions:
- Initially, the whole thing sounds broken. And it does not improve until you pass the 30 hours mark. I would say that the earphone opens up at 20 hours, and before it has a very limited frequency extension; while the amplifier took much longer (40-50 hours) to start sounding better than the SRD-X. As I have not crossed the 100 hours limit, I don't know where it will end.
- The SRM-252s has much more weight than the SRD-X, but less impact and dynamics than the passive energizers. But it is mud more portable than both.
- There is no comparison between the SRS-001 and the SRS-005 mk2. There is much more treble extension; but also the treble is clearer and smoother, with nothing of the graininess of the SRS-001.
- The bass range seems to be more extended, but also clearer and less resonant.
- The treble is still softer than that of the Lambda range. On the other hand, I have always found the Stax treble range a little bit too strong, while still listenable and musical.
- The bass is less deep and more congested than the Lambdas. In particular, the bass of the 404 Signature fed from the Woo Wee is close to perfect for my tastes - much better indeed than my Senn HD800 and AKG 701.
- The soundstage is not as good as the bigger Lambdas or the Senn HD800, but much better than any other in-ear I have tried (Etys, UE10). In comparison, the other in-ears are claustrophobic.
- comfort is the best of any in-ear. When you wear the earphones without the headband, you barely notice that you have them. The box comes with three different ear tip sizes. The bigger one was the best for me. In any case, I prefer to use the head band. I have read that many people finds it uncomfortable - not my case. Adjusting it by rotating the earphones around their axis, you can change a little the bass-treble balance, adding brilliance or bass.
- When the fit is good (and you know it from the strange "compression" noise that you hear when you reach it), the bass is good and with a decent slam - much better than the SRS-001. The slam is also better than with the Lambdas
Most of the time I listen to classical music, but most of my records are of pop-rock music. With many of my headphones, recent pop music sounds exceedingly bright. This is tamed down by these headphones, making it listenable.
I will report back when I have reached 200 hours. If I had to decide whether to keep them or not the first day, I would have returned them. Big error - no I prefer them to any other portable set up I have. You can follow the story here from now on.