Mine adds a lot of hiss when I engage either the compressor, octave, fuzz or Sans Amp. It does not occur as much with the chorus. I have tried it with my three basses: an active Status Stealth, a Turner Renissance (piezo pickup only) and my new Clement bass that only has a piezo pickup. I play through a LMIII head into a 2x10 or a 1x15 speaker. The "in pad" button does not help. I have put the gain on the LMIII at almost zero, the lower the gain the lower the noise but it never goes away. I will try it through the effects loop when I get home tonight.
Does anyone have a suggestion?
I do not see the red clip light come on through any of this.
To start, the pedal should be in bypass mode. Make sure that the headphone amp is NOT engaged. You want unity gain at this point. This means the signal with the pedal inline is the same volume as your instrument without the pedal. Try engaging the PAD when the pedal is in bypass. You should hear a noticeable difference. The Turner Renaissance uses an 18 volt preamp system which has a fairly hot output. In general a guitar with a preamp will add a certain amount of noise. Noise will add up with each subsequent device. If you run an active bass into a device like the Bass Fly Rig into the front end of an instrument amp you now have 3 preamps in series. It's no surprise that it won't be dead quiet. This is not to say it can't be made to work if every part of the signal chain is gain staged properly.
Even some passive guitars can have pretty high output. If you think the compressor is clamping down too much, engage the PAD. The OCTAFILTER is designed to get synth style square wave tones. If you want a more normal sound without the "synthy" quality turn the Q control counterclockwise and the Range control will now act like a tone control to smooth out the sound. Between this and the mix you can get some nice octave sounds. With a little understanding it's easy to make the pedal work for you. If you take it out on a gig and engage the octave, fuzz and turn the mix, Q and Range controls all the way up you will be disappointed.
The compressor should not add extra noise but will increase any noise inherent in your instrument. If you experience noise and it goes away when you turn off your instrument's volume that means your instrument's pickups are noisy.