Hello all, this is my very first message on this fine community's forum. I recently jumped the Topping D50s bandwagon, added also the Topping A50 and the Topping P50 linear power supply. The output is on Sennheiser HD650 with modded balanced 4.4mm cable and Fiio model LB-4.4mm to 2.5mm adapter, besides that I'm also listening on my rather old setup: Monitor Audio Silver 100 (first edition) and Aeron160 (italian hybrid amplifier ). I found the tube warm output adds nicely to the topping 50s rather precise sound. All this being said, I'm interested to found out what do you think about op-amp rolling the Topping 50s or/and the A50 for overall sound improvement. I'm considering the Burson V6 Vivid/Classic Dual on Dip-8 extensions in order to fit the cases. I would need three dual op-amps (even if they come usually in pairs). What do you think, would that be a sizable improvement or an overall waste of money ? Thank you for your kind expertise.