If money is an option, as it is with most of us, I recommend auditioning the stock PSA-DL-III before spending money on the mod. If you can, do an A/B comparison with the stock unit and whatever digital source you are currently using. Upon doing this myself, I found only subtle improvements, in favor of the DL-III, over my Rotel RDV-1093. I had to really do some critical listening to discern any differences. The DL-III presented a slightly more open soundstage (depth and width) and also seemed to allow greater bass response (tighter, more defined). If you are currently running a digital source of better quality than my Rotel, the differences, for you, may be even more subtle.
I went ahead and purchased a new DL-III with the Cullen Stage IV upgrades directly from Cullen Circuits. When I hooked everything up, I was shocked to hear that I could only discern a slight improvement over the Rotel (same as the aforementioned improvements with the stock unit). After about 160 hours of use, I took my new modded unit into my dealer, where the staff and I proceeded to run A/B comparisons between the stock unit and the Stage IV mod. (None of us) could discern ANY differences.
The Stage IV unit is unbelievably good. It sounds as good as any digital source I have heard. That said however, it just doesnt sound any better than the stock unit go figure. I never provided my follow up review because I didnt want to slam Cullen. The people at Cullen, including Rick, are absolutely excellent people to work with. Upon contacting Rick, he even offered to take a look at the unit and repair it if he found anything wrong that, or replace it with a stock unit (and refund for the upgrade). That was a couple of months ago. I really dont want to ship the unit half way across the country (to & from), besides, Rick doubted that there was anything out of place do to the fact that the unit operated fine. As I said, it does sound great just no different than the stock unit. For me, this subtle improvement was not worth the investment.
Since I want to build a music server anyway, and because the unit does sound good, I can find satisfaction in my purchase of the Cullen unit. I plan to go back to the dealer now that I have over 300 hours on the DAC. We (my dealer friend and I) plan on doing another A/B comparison using his very best reference system. I hope to hear a difference this time.
Keep in mind, there are many newer, quality-built, high-end/upper-midfi digital sources available that provide exceptional playback. The newer systems tend to sound better than (any or most) of the older high-end digital sources (better clocks, less jitter, improved circuitry, etc.). Therefore, if you have a pretty good newer source, you may be surprised at just how little an external DAC may improve your systems sound quality. On the other hand, if you have an older system, you are likely to hear some real improvements. I replaced an Enlightened Audio T-7000 transport and ARC DAC II (an exceptional system in the late 80s early 90s) with the Rotel/Cullen Unit. The Rotel unit alone, sounded much better than the older separates.
Note: before you write off Rotel, do try the RDV-1093. While it is primarily a DVD player, it sounds considerable better than Rotel's best CD player. It is their flagship player that retails for $1,500. I use this as a benchmark for your reference only not an endorsement for Rotel. There are many CD players on the market that are better than my Rotel. If you happen to be running something of better quality than this unit, I would not consider the external DAC. It would be to your advantage to make your requests for recommendations by including the makeup of your entire system.
Hope this is helpful.
Ben
