Getting new Preamp


Need a little help in making a decision on purchasing a New Audio Research LS 27 or Backert Labs Rhumba Extreme 1.2? I am using Solid State Amps -Aragon Palladium on the Highs, 8008 on the Low End(newer version).Infinity Epsilion Speakers.
Open for For suggestions.
lilrock
If you are bi-amping, check the recommended minimum impedance of the preamp.

Assuming both amps have a 30k input impedance, bi-amping will cut that in half.
lilrock

Eric is right one amp is 15k the other is 46k you have a combined impedance of 11kohm that the preamp will see, forget about tube preamps, unless they are less than 1kohm output or less and very important maintain that <1kohm from 20hz to 20khz.
I would play it safe and get a solid state pre they are usually around 100ohm or less, they will have no problem with this 11kohm loading.
If your hooked on tube, then get a Schitt Freya, at least with this you'll have the option of tube, solid state or even passive.  

Cheers George
One tube pre-amp designer who does so for both the consumer and pro markets is Tim de Paravicini. His EAR-Yoshino pre-amps are designed to drive a 600 ohm load, the standard in recording studios. The EAR 868L has four pair of stereo outputs---2 pair unbalanced on RCA jacks, 2 pair balanced (via transformers) on XLRs.
Check with Backert.  Small company and very responsive.
Thanks Guys for your Help think I'll stick with solid state. The Pass
Aleph P is doing fine just looking to upgrade. Willing to spend $3- $4.5k on the used market for solid state.  Any Thoughts?

Larry
Erik and George are of course correct that impedance compatibility needs to be carefully considered in this situation, given that preamp-to-power amp impedance incompatibilities tend to arise most often when tube-based preamps are used in conjunction with solid state power amps, and given that in this case the preamp would be driving two power amps.

However, given the following statement in this thread I think there is a good chance that the Rhumba 1.2 Extreme would be suitable in that respect:


BackertLabs 8-17-2018

... the Rhumba 1.2 preamp has an output impedance of less than 75 ohms, which is quite low. It allows the Rhumba to mate nicely with any power amp you might select. Thanks again and please don’t hesitate to write us, or call if you have any questions.
-Andy Tebbe
Backert Labs

The 75 ohm figure is most likely based on a mid-range frequency such as 1 kHz, and is probably a good deal higher at 20 Hz, but this statement nevertheless appears to suggest that the match stands a very good chance of being suitable.

Regarding the LS27, the 8008 MkII is spec’d as having an input impedance of 46K single-ended and 70K balanced (which probably means 35K per leg), and while various versions of the Palladium have low single-ended input impedances (for versions which provide single-ended inputs), their balanced input impedances are in the vicinity of 44K (which probably means 22K per leg). The ARC LS27, like most ARC line stages and preamps, has a recommended minimum load impedance of 20K, although it is not clear if that applies to the single-ended outputs, or to the balanced outputs, or to each leg of the balanced outputs. 70K in parallel with 44K is 27K, while 35K in parallel with 22K is 13.5K. So it is possible that the LS27 would be a suitable match if you were to drive both amps with its balanced outputs, via XLR splitter cables, and depending on how ARC’s 20K minimum load recommendation is defined. And the match might also be within reason (although not ideal) if you were to drive the 8008 MkII with the LS27’s single-ended outputs while driving the Palladium with the LS27’s balanced outputs (the resulting load impedance in that situation on one of the two signals in the balanced signal pair probably being 46K in parallel with 22K, which is 14.9K).

Good luck. Regards,
-- Al
P.S: You’ll also need to have some means of matching the gains of the two amps, of course, if their gains don’t happen to be identical. And achieving a proper gain match will probably be affected by whether you drive the amps balanced or unbalanced, or some combination thereof.

Regards,
-- Al
Post removed 
Many Thanks this is a great Help

Happy Listening to all
Larry
Just my $0.02, but there is absolutely no logical reason for a modern power amp to have less than a 47K Ohm input impedance. A lower input impedance makes it very difficult to mate a preamp (particularly from a different manufacturer) to drive the power amp properly, presuming the ratio of 10:1 is used. This is particularly true in the OP's specific situation of biamping.