HELP: is Monarchy Audio DAC a good idea?

I would auditon a Monarchy DIP at the same time. I have a monarchy 22 DAC which I drive from the SPDIF output of my Marantz CD67se. The Monarchy DACs do not reclock the input to remove jitter, so when I added the DAC to my CD player there was not much improvement (since the marantz players have quite poor jitter measurements, and the jitter is really the limiting effect on sound quality). However adding the DIP between the CD67 and the 22DAC really improved the clarity and imaging. IF you can do an audition USING YOUR EXISTING DVD player then you might want to try adding the DIP.

As an added bonus the DIP will convert toslink to SPDIF (RCA) to drive the DAC.

Bear in mind that if you audition this (non-reclocking) DAC using an expensive transport then it will likely sound much worse when you take it home and drive with your DVD player due to the jitter on the output of the DVD. The performance gap may be significantly closed by using a DIP. I would strongly suggest auditioning using your DVD player.

I used to be really skeptical of "tweaks" like the DIP, but not any more.

Think about how the waveform output of an D/A convertor will be distorted if the sampling rate is not consistent. Amplitude distortion, phase distortion. I too was skeptical, but after I heard the difference I thought about it a little more and it does make sense.
Also check out
http://www.dcsltd.co.uk/papers/jitter.pdf
which explains it better than I ever could.

It's hard to say ... your system is good, especially at the price, but not overly resolving (no offense .. you probably realise this). I'd say that you should either demo a DIP before buying, or just buy one here on Agon and worst case resell it and lose the shipping (probably no more than $20 on a small item like this). You'll have little problem reselling if you buy a DIP 24/96, and older DIPs can be found for <$100.