Trying to reduce noise while listening to tube phono

Let me start by staying that I'm in love with how my system sounds right now. Hagerman Trumpet and Decca London Super Gold (paratrace stylus) is a ridiculously good combo. The only "but" is that if I raise the level to 3 o'clock on the preamp (Herron) I start to get tube hiss... or some hiss from somewhere. It used to be worse but then I got all new very low noise tubes and it improved a ton but I want to see if I reduce it some more. I'm wondering if the issue is the amount of gain on my preamp? Should I try another preamp with more gain and see if that solves the problem? On other inputs there's no hiss even at full volume so there's nothing technically wrong with preamp.
I've had similar experience since going from an old ARC PH3SE to the new Herron last year. Keith assures me its not the Herron and I believe him. Especially since the noise definitely does change when I mess with the phono leads. Not sure why its more of a problem with the Herron than it was with the ARC. But it does reinforce my experience with phono stages which is that even the best of them are the most temperamental and idiosyncratic of all components. With the possible exception of step-up transformers!

In my case, while the noise definitely is a lot more than I get from any other input still it is just barely at audible level from the listening chair and in any case less than groove noise from all but a few of the most silent pressings. Which is why in the big scheme of things it is way down on my list of things to work on.

Early on it was much worse though. So it is probably something you can reduce if its that big a priority. 

Things that helped for me, including some suggested by Keith:

Clean everything with alcohol. Just plain alcohol and a clean cloth. No contact conditioners.

Experiment with phono lead routing. Sometimes they like being together, sometimes apart, and sometimes even a small change makes a difference. I use Scotch tape once I get them where I want.

You can make your own shielding from battery grounding strap. Its actually a mesh tube that can be slid right over the interconnect. If you think this might help you can test it out first by wrapping aluminum foil, just tear into strips and wrap, being sure to go all the way to the end of the RCA.

RFI could be a problem, anything could be the source, flip off breakers to everything, unplug everything, then reconnect/power on one thing at a time. 

Static electricity is a problem. Mine isn't bad enough to make white noise but it definitely affects the sound. Static-Guard anti-static spray for laundry works great. $3 at Walmart. Don't spray right over a record but do waft it around the turntable and over all cables. Do it right before playing a side.

When I did all this stuff and still had a problem my last ditch effort was to replace the RCAs. Went to solder new ones and it turned out there was a bad solder connection! Not likely what you have but you get the idea, all you can do is check and check and check until you find it.

Thank you so much for this! I'll work through the list and see what changes.
Experiment with phono lead routing. Sometimes they like being together, sometimes apart, and sometimes even a small change makes a difference. I use Scotch tape once I get them where I want.

This has already worked. I use a wall shelf for my TT and I'm guessing that the lead was picking up noise from the power line inside the wall. When I moved the lead away from it, the noise reduced by 50%. Not completely gone but now way below the threshold of the music. Thanks again!
dhcod you did the right thing getting the low nose tubes. Assuming they are the lowest noise tubes you can get that is as good as it is going to get with that phono preamp. It is called tube rush. Your preamp is fine.
This is much different than a hum which can be caused by a lot of different things. I'm sure once you put the needle down you can't hear it.
As the background noise of vinyl greatly exceeds the noise of even noisy phono stages.
That is what I thought too except as millercarbon pointed out, there's more too it. Until I got the phono leads into a better position, I didn't realize how much noise I was dealing with beyond tube rush. It sure sounded like tube rush but it wasn't.
The leads from the Tonearm or from the Phono amp to the preamp?
Tonearm leads. Mine are very fine non shielded cables that run from headshell to RCAs. I really should have realized this a while ago.
So we got lucky. And thanks to mijostyn learned something about tube rush as well. Glad I was able to help.
That's why. What is the reason to have unshielded tonearm leads?
The first tonearm I had was an ADC Pritchard. It came with the Thorens TD 124 that I bought use. It was a wood tonearm and the wire within the arm was unshielded. As the arm got closer to the motor the hum increased. This all disappeared after I put an SME on it. Unless there is something special about that wire I would consider rewiring the arm. If there is something special about it I would love to know what that is!
...just for the heck of it....plug your pre into a different wall socket.
Just buy my phono so quiet!  LOL!

Happy Listening.
Dedicated AC lines eliminated noise problems from my system. Just a thought ...
goheelz why would a dedicated AC line eliminate noise problems?
Dedicated AC would help, and usually does help, if there are other devices otherwise attached to the same AC line that produce electrical noise in the form of EMI.  It could make a big difference if you've got your refrigerator or dishwasher drawing from the same circuit breaker, for example.  For that same reason, the turntable motor should be electrically isolated from the preamplifier and amplifier. But these precautions would do nothing for inherently noisy tubes or a poorly designed noisy circuit.  
+1 @lewm Who, unlike me, may have the technical expertise to explain *why* dedicated AC lines helped with noise issues. Thanks for your cogent summary of the way AC lines can be a factor.

Agree that phono stage design is likely a culprit in the OP's noise situation. But I'm sold on dedicated AC lines, whether I can explain their efficacy or not!

What is the reason to have unshielded tonearm leads?

I bought the M2-12R from the dealer who suggested rewiring it in this manner for better sound. It really makes a difference.... SME's wire has never been their strong suit. I'm super happy with the arm so I would definitely look everywhere else for solutions rather than rewire.
If you live in a low RFI environment, you might not suffer for lack of shielding.  I use unshielded tonearm leads in my suburban environment, for some of my arms, and I don't perceive a problem.  Which is to say that my tonearms using shielded wire sound the same as those using unshielded wire, in terms of RF noise. If you live in a city or industrial area, shielding is a good idea. Furthermore, I would think that the SME arm wand itself acts as a sort of shield for wires traveling within it.  Not so, once those wires exit the base of the tonearm.  On the other hand, I have never read that SME used inferior wires.  Is there any reliable source for that info? (Is there any reliable source for anything in audio?)
First rule of shielding is to protect the signal “ground” also. You need to replace your simple unbalanced fake-“shielded” cable from your tonearm to the phono stage with cables that have fully shielded twisted pairs, one cable per channel, such as Belden 1696A. The shield drain wire connects to the tonearm ground at the turntable side, and to the phono stage chassis ground at the other side. Make sure the tonearm ground is isolated from the turntable chassis. All interconnects should be made in this way for line level signals, except the shield drain wire only connects to chassis ground at one end - with the preamp usually being the most suitable end. 
Regarding the SME wire..... I was going to replace the tonearm cable only which just from anecdotal evidence from owning a couple of their arms in the past and also from people I've known that have upgraded from the stock cable, aren't great.  The dealer suggested he had really good results with a rewire from RCA to the headshell so I did it.