I-Dac or Moon audio 100D

I haven't been pleased with how my system plays classical music. It sounds muddled. It was suggested I upgrade my source. I'm using a Muscial Fidelity V-Dac and an Onkyo NS dock, which bypasses the IPod internal Dac.
It has been suggested that I replace both with the Idac or I just replace the Dac with the Moon Audio 100d.
The rest of the system is a Music Hall 25.2 integrated amp and Focal Chorus 706V speakers. I'm using Belkin speaker cable from Blue Jean and Audioquest Blue Racer II interconnect and Audioquest coaxial cable.
Thanks very much for any insight.
I have a Moon 100d and it is very clean sounding. Definitely would recommend it.
The 100D uses the BurrBrown PCM1793 chip, which is very accurate from what i know.
People have reported reliability issues with the iDAC. I haven't owned one, so no personal experience. There's a thread here somewhere.

Simaudio makes rock-solid stuff. And they're very clean sounding.

Are you sure it's the source and not the amplification?
Thanks. It seems to make the most sense. I decided to go with the Moon, with a 30 day trial. I should find out soon whether it is an improvement.
The Moon 100d sounds great. It was dramatic improvement right out of the box. Thanks very much for the input.