Hissing sound when Tone Control is turned on

C11, C20s, C2500, Mx110z, Mx120.  A few.. When they are tuned up and running they are quiet..

Did you buy it new? Did it just start making noise or out of the box. it made noise?

They make music, not noise..:-) This summer 50 years with Mac.. YUP I'm a Mac guy.. I like their older valve gear.. MC225, 240, 275, 30 and 60s. I don't currently own ANY SS Mac Power amps.. Just valve.. I have a Cary V12R I really like with a Mac front end... Just perfect for me.

I use class Ds to do all the bass duty.. Actually I'll be swapping over within a month or so.. See how the weather act.. Class D, for the main monitors in the summer too. Valves are just to hot.. It gets to be 110 + here where I live..

Regards

I bought a 1.5 year old pre-owned C49 preamp from my Mcintosh dealer. So i had no idea about how this preamp functioned when new. That was why i was hoping to get some guides from Mcintosh users first.

After some time-consuming tweaks on settings of preamp and power amp, I was finally able to track down the problem, The hissing sound during idle can no longer be audible if the output gain on my Parasound A21+ power amp is set to appropriate matching level. I had to turn the gain level down to almost minimum to get rid of the hissing when Tone Control is enabled on my Mcintosh C49 preamp (of course turning off the Tone control is another less preferred option). My previous setup was pairing my Parasound A21+ power amp with Parasound P6 preamp and Parasound official recommended the output power gain for both channels to be set to maximum all the times. And the parasound P6 and A21+ combo were working beautifully as well. I guess i should have done this equipment output matching practice before i raised my concern, especially when i pair the Pre & Power amps designed and manufactured by different brands. I am still new to hi-fi world so i learned an important lesson today.

Thank you for your valuable inputs anyway.

Happy Music Listening !

Juicy good my friend, you found an answer.. Parasound, that is another under appreciated amp.. I have a ZPre3 I use with a C20 to add a remote control and all the goodies of an OK DAC via a tape loop.. Just needed to do a little matching.. Even added a sub out option, still sounds like my C20 100%, serious little preamp.. GREAT phono stage MM MI and an MC with 56 db of gain.. (52?) It has a wonderful bass contour for the phono/tape section.. attenuated bass step baffle. 

I hate noise.. LOL 

Regards

Overall i have to patiently tweak and find the best matching gain levels between my MAC C49 preamp and Parasound A21+ amp.

Here is a thread found in AVS Forum, members were also discussing the similar topic : https://www.avsforum.com/threads/parasound-owners-thread.1122095/page-332

Get gear without tone control... apart from L/R balance you should not need any