I’m not familiar with your classic headphones so I cannot comment on synergy, but I can recommend the Burson Conductor V2+ which mates very well with my Audeze LC-2, it has a sleek design and good build quality, plenty of power in pure Class A, a pre section, and a very good Sabre 9018 based DAC supporting PCM to 32/384 and DSD256, sound wise pretty transparent and dynamic yet musical and non fatiguing for longer listening sessions.
Burson have now released the V3 version which is based on the newer Saber 9038 DAC chip and at a retail price of 1750$ but I think you should be able to find a used V2+ within your budget...
Happy hunting
