One inexpensive thing to improve the sound is to turn off your TV when you are not using it. :)
Your speakers are very nice, that's for sure. The amp sounds like a pretty good one too. There seems to be a gap with volume knob (back of the amp is not the best, probably) and in converting what is on the plastic discs into an analog signal. That Marantz model is not on the same class as the amp and specially the speakers.
If you want just the one box, the iDecco has had good reviews. The Tact dac/preamp combo is around your budget (used). The Benchmark dac includes a volume knob at no extra cost and it might still have a 30-day return period.
If you want to get two separate boxes (dac and preamp) then that's more fun because you can spend $1000 on each one. :)
Your speakers are very nice, that's for sure. The amp sounds like a pretty good one too. There seems to be a gap with volume knob (back of the amp is not the best, probably) and in converting what is on the plastic discs into an analog signal. That Marantz model is not on the same class as the amp and specially the speakers.
If you want just the one box, the iDecco has had good reviews. The Tact dac/preamp combo is around your budget (used). The Benchmark dac includes a volume knob at no extra cost and it might still have a 30-day return period.
If you want to get two separate boxes (dac and preamp) then that's more fun because you can spend $1000 on each one. :)