buy pulling out the cable slightly your turning a stereo (trs) cable into a guitar type cable (ts). that's what your pan thing is, you could just (if your headphone amp has it) press the mono button on the channel, that'll put it out thru both sides.

I have a feeling it may have something to do with the laptop output not being a true line-out but I have used other headphone jacks this way without problem.

i'd double check the cable your using, make sure it works the way it should. what your doing is not ideal, but it certainly can work. providing the cables work, and there aren't any strange power issues, all you have to do is make sure you don't put the headphone out so high/loud that you distort the headphone amp in. i suspect a bad cable, or incorrect connection.

I have tried the mono buttons on the amp still same buzz.

When I disconnect the 1/8 to 1/8 cable from the laptop and have it fully connect to the headphone amp I can hear left buzz when touching the other side of the plug as well as the right side of the headphones. So both connection of the cable seems to be getting signal.

But in anycase Im thinking that 1/8 cable may be bad as it is having problems in other applications.

Going out to get a new cable, hope that fixes.

Thanks

It really sounds to me like you have a twofold problem going?

Firstly, 1/8 inch TRS plugs are all notoriously simply awful. The best in intermittency. So you get some gold plated ones and replace those nice shiny chrome ones with the gold plated ones. Do that first. If you can purchase them premade? More power to ya. If not? Time to get out the soldering iron and order some good goldplated plugs.

Secondly, there are huge problems with ground Loop hum when most anything gets plugged into the computer that happens to be plugged in to another wall outlet somewhere else in your room. And even if they are plugged into the same outlets, ya get a ground loop on that 1/8 inch cable. So you can lose the plug and the wire grounded on the source feeding side. And disconnect the ground wire from the plug on the input receiving side. Or, you could simply take your computer power cord plug and insert a 3 into 2 AC ground lifter. And most of your problems should then be solved. Beware though, any guitar amplifiers with tubes that have had their AC plugs screwed around with them the ground pin removed, with a new one replacing the old one but wired backwards, can pose a deadly shock hazard. Nothing to screw around with if you don't own an AC voltmeter. And ya make absolutely certain when you plug things in to check the ground on one device against the ground on an other device. You will still likely find some voltage? It should be fairly low. Though you could see it as high as 60 V. As long as you're not looking at 110 V or, 220 V elsewhere in the world, you should be good to go. But you'll also want to make that same test and check if anyone else brings in their own guitar amplifiers. You just simply connect one test lead to the metal housing of a plugged in microphone. And you connect the other test lead to the chassis ground of the unknown guitar amplifier. You don't want to kill any of your clients. So don't be lazy. Don't be too self-assured. Never assume that nothing will happen.

Can't get enough of that funky stuff.
Mx. Remy Ann David

I bet when you unplug the laptop powersupply most of the noise go away. using a ground lift can help + make the laptop output to its maximum volume and lower the gain of your headphone amp. it'll be better.

but remember the headphone output is a preamplified signal not ment to be amplified again.

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