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The Cavalli CTH, especially massdrop version is very good companion to HD800S in term of price and quality.
There is opinion floating in the net, that High impedance Sennheiser (HD600,650,700,800,800S) slightly more beneficial from valve amplifiers. Brings "buttery smoothness","liquidity", "warmness" ets.
It is totally depends of personal preferences, in fact that valves do the reduction of...