McIntosh C39 noise

Any Mac C39 owners or others in the know who can tell me whether it's normal for C39 phono stage to have noticeable hiss beginning at volume level 30 or 35 out of 100% (with no source on to contribute)? Gets pretty bothersome at 50, and is much higher than my old, cheap preamp. Has both hum and hiss spectrum to it. I don't usually turn it quite that loud to play, but it makes me think the noise floor should be better. Running VPI TNT, Rega 900, and Shure V15. Any unusual grounding issues with this, as the arm has no separate ground wire, and the pre has no separate ground plug on the cord?
I never had a hiss, but when I had a C39 I went nuts trying to find a phono pre-amp to work with the C39. I tried about 7 units before I found the Naim Stageline and Hi-Cap power supply to no create a hum. McIntosh told me it was EFI/RFI and to try sheilding. I spent a couple of hundred dollars in Mu-Metal and other foil wrapped sheilds, non helped. It was the C39. I traded it in on a MX132, now I still have the Naim so I can't say if it was solved or not. The noise floor on vinyl definetly is improved, actually I traded the 132 in on a 134 and am now waiting for a MX135. So I didn't lose faith in Mcintosh. Is your cartridge MM or MC? Mine was MC but the problem started even with a Grado MM. Good Luck
I have c2200 and the shure v15mxr and lots of noise but at louder levels (55-60). Light dimmers and ac motors seem to contribute. My ic's are nordost red dawn and they have no real sheilding so just touching them increases hum . Cables with better sheilding reduce noise greatly but I also lose the fine detail, speed and openness of unshielded cables. I'm looking to combine nordost sound with better noise rejection. Grado cartridges have same issues, maybe music man with higher output and better cartridge shielding is an answer also but that costs twice+ the shure and no user replacable stylus.