Tekton or Klipsch

Since at least in theory every component in the string influences the sound... what might the Rothwells do?

There have been conflicting reports here about the Rothwells. Some people have reported finding that they compromised dynamics; others (including me, in my case with the 10 db version) have used them with fine results.

I suspect that in some of the situations in which compromised dynamics have been reported that the cause was using them to drive input impedances that were low and/or that varied significantly as a function of frequency. I don’t think that would be a problem with the Brio-r. John Atkinson measured the line-level input impedance of the similarly spec’d non-r version of the Brio as follows:

...its input impedance at 20Hz and 1kHz was, at 41k ohms, fairly close to the specified 47k ohms. Though the line input impedance dropped to 36k ohms at 20kHz, this will be inconsequential.

A concern with the Schiit Sys would be that its input impedance is only 10K, which depending on the particular source components might be too low to be optimal. Based on measurements I’ve made of the 10 db version of the Rothwell it would present the source components with an input impedance of 30K when used in conjunction with a 41K load. And that figure would most likely be higher for the 15 db and 20 db versions.

Also the Sys would require cables on its output side, which the Rothwells would not.

Regards,
-- Al

Even now with the Kef’s i rarely go past 9 o’clock position. Sometimes maybe 10 when I’m listening to vinyl.

That’s definitely a problem, if you want to continue to use the Brio-r with one of the high sensitivity speakers that have been discussed. Stereophile measured the sensitivity of the LS50 as being 84.5 db at 1 meter for an input of 2.83 volts (the spec being 85 db). Roughly speaking the choices that have been discussed are about 14 db more sensitive than that.

Although this photo shows the front panel of a passive preamp I believe the dial markings for the volume control are reasonably representative of the characteristics of rotary volume controls that are typically used in active preamps and integrated amps, in terms of db of attenuation vs. position. As you can see the 9 o’clock position corresponds to about 37 db, so with speakers that are 14 db more sensitive the listening volume you presently hear at the 9 o’clock position would be produced at a setting of about 51 db, not far from the bottom of the range. And as you can see, near the bottom of the range adjustment resolution becomes much coarser than at higher settings (6 db per marking increment vs. 2 db at higher settings); channel imbalances may occur, depending on the particular control; and as Auxinput pointed out earlier the amp may simply not sound as good.

Assuming your sources don’t provide a volume or output level control the one solution that occurs to me if you were to use the Brio-r with one of these high sensitivity speakers would be to insert a pair of Rothwell attenuators into each of the pairs of input jacks of the Brio that you are using. Probably the 20 db version of the attenuator for the digital source(s), and the 15 db version for vinyl.

BTW, generally speaking I would recommend against in-line attenuators made by manufacturers other than Rothwell, as some of them have input impedances that are too low to be suitable for use with many source components. That will rarely if ever be a problem with the Rothwells.

Good luck. Regards,
-- Al

A point to consider in going from the LS50 to one of the high sensitivity speakers that have been discussed is that if you are using a digital source (as opposed to or in addition to LPs), the somewhat highish gain of your integrated amp (the gain of the Brio-r from its line-level inputs can be calculated to be about 40 db) might result in having to utilize the volume control at undesirably low settings (where channel balance and/or resolution of volume adjustment may be compromised).

As a rough ballpark approximation in this case figure on the volume control being used at a position that is around 90 degrees of rotation below where you are presently using it. Although less than a 90 degree difference if you are already using the control in the lower part of its range.

Good luck. Regards,
-- Al