Rothwell In-Line Attenuators?

Just wondering if anyone has used these? are these really audiophile quality? I have a big mac amp mc602 and a set of high efficiency tannoy speakers 15dmtII.
It's just a couple of passive parts so there is no reason it wouldn't be.

If it solves your problem (I'm assuming too much overall gain) and you otherwise are happy with your system then I think they are good way to go. If you can solder you can build your own for about $5 worth of stuff from Radio Shack.
I'm using a pair on one of my amps to lower the gain from the pre-amp. Can't tell they are in the loop.
I've used them with good results to lower gain.
I've used them, and they work as advertised, but I think they are no better than the less expensive FMOD attenuators, which come in a variety of attenuation levels (3,6,9,12 dB, I believe). You can get them from
Dare I put in a dissenting report? I tried a pair, and in my usage noted, as advertised, a reduction of gain. But I also noted a slight veiling of the sound, particualrly in the upper frequencies-- I was conscious of their presence in the system, and took them out. YMMV.
I'll have to agree with Swklein. Anything added to the signal path will degrade the sound
I agree that anything will affect the sound, but I can't go along with it will always be degraded. In this case we are talking about two high quality resistors, a few solder joints, and an extra connection. I can see where using these could change the load on the preamp and degrade the sound, but if the values of the resistors are properly chosen you could maintain the same load and attenuate the level. In that case, whatever slight change in the sound occured could easily be outweighed by the benefit of operating the preamp further away from the lower limit of the volume control.

According to what I see on Rothwell's website these come in only one configuration that they claim has been chosen to "work well" with just about any combination of input/output impedances you are likely to encounter. One has to wonder if Swklein's equipment wasn't a good match for them. I find it hard to believe that the values they settled on are the ideal for all applications.

If Swklein tried them on the AR amp he currently has listed with an input impedance of 100K ohms using an AR preamp that one would have to assume is optimized to work into that load, I can see where an attenuator with a different input impedance could adversely affect the sound.

That is why I would make my own, or better yet pad the input to the amp to reduce the gain and get rid of the extra connection. That way you could experiment with different values until you found a good match for the equipment. On the other hand, they are pretty cheap in the grand scheme of things so you don't have much to loose by trying them.
As mentioned, I used these attenuators. And with high quality gear. I would suspect that they did affect the sound somewhat. BUT the reality is that the benefits gained from their used greatly exceeded any subtle negatives caused from their inclusion in the system. They enabled the satisfactory use of existing gear. If they were not in the system, I'd have had to replace either my amp or speakers.
These attenuators, or ones you could make with a few resistors, are no different from the multiposition Attenuators costing several hundred dollars that some audiophiles prefer to pots for gain control, except that they are permanently set to one particular value of attenuation. Of course, switch contacts are also avoided. If you don't use an attenuator what will you use? Probably a pot in the preamp or power amp, and that ain't exactly perfect.