Thanks for the info SilverEars. Doesn't look good. I've plugged them into everything I can get my hands on at the moment which isn't much... a MacBook Pro, an iPad Pro (< 2 ohm output impedence allegedly), a Topping TP21 class D amp and an analog synthesizer. None of these are great tests but I...

Thanks for your reply. Only one way to find out if it is the amp or not..

Hello I’m experiencing some distortion with my Shure 1840 cans when driven from a SPL Crimson DAC/amp interface. The SPL headphone output impedance is 33 ohms which is apparently pretty high. The Shure 1840s are 65 ohm 96 dB/mW sensitivity. When driving a pair of old K240M 600 ohm headphones I...

Are you grounding the Rega through some ground pin on the pre-amp? It's been a while since I've had to tackle a ground loop hum issue. There are many articles on the web about this. Sometimes it can be a domestic appliance like a fridge or washing machine causing it. According to the analyser...

I have Sennheiser MX475 which go for around $30. Definitely an improvement over the wired Apple buds I've tried in the past. The 375 isn't much different apparently. The 575 has an inline volume control but is a bit more expensive. No inline mic I'm afraid.