Don't own one, but played a few before. A noisegate is a must when you're using any of the 6505 series, as far as I know when you use the Noisegate going into the fx loop of the head it's supposed to reduce the overall hiss and noise the amp gives you (you won't be able to silence your pedals at the same though I think). The 6534+ head has an internal noisegate if memory serves me right. Agent Orange will surely chime in and give you his experience, he owns said head.
I do indeed own a 6534+
I have A/B'ed it with a 5150 II, which is what the 6505+ was called before EVH pulled the pin on Peavey. The 6534+ is 'tighter' sounding and has more mid-range cut (i.e., has stronger mids that 'cut' through the mix more). The cleans are also cleaner. The 6505+ might have slightly more bottom end, but the whole series has a little too much bottom end if anything. I tame the bottom end of my 6534+ with a tube screamer (in my case a Maxon OD-9) and most people with the 5150/6505 series amps do the same thing.
I would say that the two amps are very similar in terms of how you operate them, just that the voicing is different due to the 6L6/EL34 difference and some revisions to the preamp in the 6534+ - and both work equally well, it's really just a matter of taste. Both have the same EQ controls and the same footswitch. This is the major difference between them and the 6505, which only has one EQ stack and you use the same settings for rhythm and lead 'channels'. The 6505+ and 6534+ are true two-channel amps
I would like to explode the myth of an internal noise gate in the 6534+ once and for all. There is no such thing. It is as noisy as a 6505+
The fizz comes from the preamp.
I would strongly recommend the ISP Decimator G-String II based on my experience of it. You set it between 11.30 and 12.00
You need a noise suppressor after the preamp, in the loop. I place mine after the MXR 10-band EQ, which is another standard add-on for these amps, but before the flanger, chorus, and delay. I set the delay up with a short time and use it instead of a reverb to thicken the sound a bit. I've always been a bit of hater when it comes to reverb so I don't miss it. If you were to get one I guess you could use a Hall of Fame.
The advantage of the ISP G-String is that it senses when your strings are vibrating and suppresses other noises without cutting off your guitar signal too much (unless you wind it up to 2 o'clock or higher, but then again some people deliberately use that effect). The regular model of the Decimator does not have this feature. Regardless of which Decimator you buy (the G-String costs more) place it in the loop. EQs make a bit of noise so put it after that.
My signal chain is as follows:
Guitar -> Dimebag wah -> Polytune tuner -> G-String guitar in/out -> MXR CAE Boost -> Maxon OD-9 -> EVH phaser -> compressor -> 6534+ preamp -> EQ -> G-String Dec in/out -> EVH flanger -> Wylde chorus -> carbon copy delay -> 6534+ power amp -> Orange PPC412 cabinet (V30s)
The cabinet is getting better as the V30s break in, but I'm still in two minds about the V30s. I might have been better off going for something with Eminence V12s in it, but I think it will be fine once completely broken in
With the signal path you may see pedals there that you don't want to use or don't have (I could do without the compressor for sure) but the order works well.
A have a box with three distortion pedals in it - an EHX Metal Muff, a Mooer Black Secret, and an MXR script reissue Distortion + - and there they stay, off my board. I find them useless with this series of amps. If you want more gain that you are getting from your tube screamer, put a boost in front of it like I have. Usually the gain on the TS is set at zero, with the level dimed. I keep my tone right down, others have it at 12 o'clock.
The boost allows you to set up one level of gain for most of your playing, and then kick in higher gain when you want it for a solo or something. I set up the rhythm channel for clean and/or 'overdriven' rock sounds with either the 'crunch' or tube screamer on. For example if you are playing one of those noisy hammer-on leads that you get on old Celtic Frost records or an early Carcass or Massacre type dive bomb then you might want to kick in the boost
My friend with the 5150 II uses no pedals at all!! He goes for a very scooped sound though. He seems to dime everything except the mids, which he set around 1 on the dial. Works for him. He has the standard Peavey cabinet too. They aren't that worried about that, and I don't think you can hear the fizz over the rest of the band. The fizz is really only annoying when practicing at home by yourself or playing in a studio, and when they go to the studio the engineer uses various tricks to cut it out.
The pedals I'd suggest getting are a tube screamer, a decimator, a delay, and a 10-band EQ. These seem to be the ones that most people feel they use all the time. The others are only for fancy pants stuff or people who suffer from GAS, like myself (and probably most on this forum). That said, when I occasionally play clean I do like experimenting with the MXR Custom Comp and Black Label Chorus, which can give you some really nice sounds on clean, and even clean up your signal a little in terms of the compressor. If you don't play cleans I wouldn't worry about those. By 'fancy pants stuff' I mainly mean the two EVH pedals (phaser and flanger), although there are some simple songs (such as some of The Exploited songs) which actually use such effects to spice up otherwise simple and repetitive riffs.
I should add in response to Effigy's comment above that my Maxon OD-9 does not make the kind of noise that he seems to be suggesting the Ibanez TS-9 makes. I find the amount of noise to be the same regardless of whether the OD-9 is engaged or not. I believe though that some small changes to the circuitry and switching have been made to the OD-9 since the '80s (when they were sold as Ibanez TS-9s).
The noise seems to come from the gain stages in the preamp.
I would recommend though placing the tuner before the G-String if you get one. With it afterwards I was still getting odd 'wash' noises through the amp when I tuned. I moved it around and the sound disappeared.
