In case you're still interested there is a direct equivalent phillips valve (can't remember what it is off-hand, but I think it's now supplied with the modern HD83 equivalent (Headphone3??) so check the World Designs page). They look and sound exactly like the mullards so I suspect the only...

Hi, I've got both models, and in a direct comparison the HD600s are less brash and toppy than the ATH-911s. This can initially sound like a reduction in detail, however the HD600s also (IMHO) exceed the ATH-911s in staging and resolution of individual instruments, so it's probably more down...