Audio Research Ref 5 SE ting noise

Recently bought a used ARC Ref 5 SE from a dealer. I am in love with the sound! I noticed that when i switch inputs - there is a momentary "TING" noise that comes out of the speakers. It's almost like a very sharp bell sound. I hear it in both channels. It doesnt vary with the volume level. The tubes have about 1600hrs on them. 6H30Ps are Electro harmonic and the 6550 is a JJ Black Sable. I am connecting with balanced connections. Turning the upstream DAC on/off doesnt seem to make a difference. I might call ARC sometime - but wanted to check if others have seen this issue.

Upscale audio FAQ section mentions something about this - not on 6H30Ps - but other types. 

The 6DJ8/6922/7308 family of tubes is a special lot and are prone to be sensitive to vibration. That does not mean all of them are microphonic by definition; though some are. What's this mean for you? In high gain pre-amps, you may hear a slight "TING!" when flipping some switches. Usually this is caused by the grid wires picking up vibration through the tube pins. We listen to each tube in circuit and ship tubes according to the product it goes into, in order to give you the best results. If you own a preamp from Audible Illusions or CAT (to name a couple), and you experience a slight ring for a second when you bang on the pre-amp or flip switches, don't sweat it... unless you plan on playing bongos on your pre-amp while the music playing. I must say... if that's your plan... you may want to re-think your strategy.
That’s the sound of the sharp switch vibration being picked up by a tube that’s gone more microphonic than normal.
Turn the volume control up to normal position (no music playing) and with your finger nail "gently" flick the top of each tube and you’ll hear the one through the speaker that’s gone too microphonic. This also adds a false euphonic's to the sound liked by some at first.

Cheers George
you were spot on George! A slight flick pretty much reproduced the issue. I had the dealer send me some new tubes. While the new tubes (Sovtek 6H30P) arent as bad as the old ones (Electroharmonix) - they also make that noise. I am wondering if the 6H30Ps are inherently sensitive. If this doesnt affect the system in anyway except when i flip inputs - can i just live with it?
I experienced exactly the same behavior with my ARC Ref 40. New tubes, old tubes, dampers including Herbies or not, it’s just endemic to the design so don’t worry about it
thanks! that makes me feel better! i have another issue i could use help with. I notice on this pre-amp that it makes a rather audible hissing noise on the speakers when i use RCA connections. When i switch to XLR - it goes away. Both RCA and XLR cables i use are not ultra high end - but they are well shielded. This happens whether a source is connected or not. I called Pass Labs (my amp) and they walked me through  procedure to short pins 2 & 3 on XLR input (normally 1  & 3  are shorted to use RCA). They asked me to remove the connections to the preamp and observe if any hiss came and that what i was left with was the noise of the amp. And it was dead quite. Which leads me to suspect the preamp. I can always switch to XLR - but i prefer RCA as it gives me a much higher i/p impedance on my amp. I also feel the bass is better on the RCA. I called ARC and their position is if the XLR doesnt hiss - the RCA is just a grounded version of the XLR signal. They dont feel anything is wrong. Short of switching to XLR cables - are there other options? Have other ACR users noticed a noissy/hissy RCA connection?
you were spot on George! A slight flick pretty much reproduced the issue.

You could try these also for the others, far cheaper than audiofool ones.
Just don’t make them too tight, I have seen it kink the glass over time, and they must be the high temp ones.
Put a couple of them on each tube, even amp output tubes.

Cheers George