ARC LS25 mkII noise level


What are the expectations on the ARC LS25 mkII noise level? Are these units supposed to be dead quiet in the system?

Mine adds considerable noise to the system. I swapped it out with another preamp (solid state) and the difference is quite significant.
jazzgene
Also, try to float the AC ground on the LS25 temporarily. See if the hum/noise go away.

The guy you need to talk to at ARC is Chris Ossana. Helpful and technical Guru.

I have a pair of Classic 120's and Ref3 LE both with many upgraded parts in the critical signal path and power supplies. When the amps are on and the Ref3 is off, there is absolutely no noise or hum coming out of the speakers.
When the Ref3 is turned on and i select any source (except phono) with no signal and turned the volume to the max, there is only a very faith hiss that i hear when i put my ears to the speakers. Selecting the phono input while the phono stage is turned on with no signal, i can hear hiss or what they call "tube rush". However, that is to be expected from tube phono stage. Mine is a Ref2 Phono.
Tube amplification nowadays CAN BE quiet although no quite to the level of a good solid state design.
Good Luck.
I did float the ground on the ls25. Also on the power amp. No change. I'll test by disconnecting all sources one by one to see if there is any change.

Your setup's noise level is what I would expect. I do think there is something going on here on mine. But if I take the LS25 out and replace with a solid state preamp, the noise is gone.
I have the LS-25mkII and have had it for about 5yrs. and have never had any issues with noise. I'm talking standing right next to speaker with ear to tweeter!
Sounds like it could be in the power supply(just guessing)
If you can do without for about 3 weeks, I would send back to ARC.
The hum/hiss is also speaker dependent. The higher the sensitivity of the speaker (92db vs 87db example) the more likely you are to hear the hiss.
What you are hearing is precisely why I have changed over to a solid state preamp. I have the tubes in the amp. It is even more troubling when listening to a tube phono preamp. The tube noise of the phono signal is very noticible. I prefer solid state phono pre for that reason. Amplifying the signal through a preamp is where you do not want extra noise. Finding good tubes that are quiet enough for preamp use is a particularly difficult feat. They may advertise them as quiet, but when you exchange out the tubes for solid state, the difference can be pretty significant.