I agree with swamp & George - The Benchmark DAC/Mac-mini is at least very good (DAC1) to xlnt (DAC2, and 3) - you did not say which one you have.
Get speakers you like (say Vandies or Maggies) and then buy a tube pre-amp (say a used Audio research). The Benchmark amp is outstanding by all accounts and the tube pre- will give you the warmth and liquidity you want. After that you can try some things to reduce noise, but the Benchmark DAC is so well-designed that the usual tweeks for inferior DACs may no help much.
So focus on room treatments after getting your speakers.
A lower cost option is a stack of Schiit units
Get speakers you like (say Vandies or Maggies) and then buy a tube pre-amp (say a used Audio research). The Benchmark amp is outstanding by all accounts and the tube pre- will give you the warmth and liquidity you want. After that you can try some things to reduce noise, but the Benchmark DAC is so well-designed that the usual tweeks for inferior DACs may no help much.
So focus on room treatments after getting your speakers.
A lower cost option is a stack of Schiit units