I guess it depends on what the mods are and which DAC you compare them to. How can one make a generalization about this?
I own the Oppo and feel it's grand for what it is. However, it is a $200 machine, thus the transport assembly cannot be too expensive and all other parts surrounding it must be cheap. I would not drop hundreds into a mod on this unit as it may fail in 2-3 years. Do the DAC thing (I mated an upgraded Assemblage 2.0 with mine) and experienced much better audio. If the Oppo dies, buy another.
I see no good rationale to modify a cd/dvd player for better DAC. If you need a better DAC doesn't it make better sense to just add the DAC and use the player as a transport? Essentially that is what your then using the original player for. I just think depending on what mods you do to a piece of gear, it could loose all its value if you ever wish to sell it, as you'd have to find a buyer that not only wanted the original piece of gear, but who appreciated the mods too and was willing to pay a premium for both. Meanwhile just adding a DAC, you always have two stock pieces of gear, worth whatever their worth, with no 'story' to tell to sell them.
Also, having seperate gear you can always upgrade one without the other.
I dunno though, just my 2 cents worth.
I agree with you conceptually, however I own an EVS level 2 mod'd Oppo 970 and all I can say is WOW! It is a really incredible player. I'm seriously considering buying a backup unit to use for parts in the even that the original unit fails.
I've owned some very good and pretty expensive players over the years. I've also owned some pretty nice DACs. The EVS mod'd Oppo was the first unit I've ever stuck in one of my systems that actually transformed the system vs just adding an incremental improvement. It made my modestly inexpensive system sound like a completely different beast.
I understand both sides of this argument and could understand the logic of adding a DAC vs modding the unit, but I am very comfortable with recommending the EVS mods if you are interested in that type of setup. One potential benefit of the mod'd unit is that the variable volume control allows you to attach the mod'd Oppo directly to a power amp if you have a single source system. Even though it is in the digital domain, I don't think the volume control works on the coax output.
In most cases, adding an external DAC box is redundant, and introduces more noises, cabling, connectors, circuitry etc.. You will get ALOT more performance with the mods to the players internal DAC/Analog output section versus adding an external DAC box with stock circuitry. Plus you need to spend extra money on power and digital cabling, for what? a small improvment in sound? The mods bring a ton more improvement across the board (and minialize circuitry as well) for considerably less money spent.
Before I bought the mod'd Oppo I would have agreed with you completely. However, after having owned the EVS level 2 mod'd Oppo 970 I've changed my way of thinking.
It is a shockingly good cd player. I have a well regarded non-OS DAC in the house, and I can say without a doubt that the mod'd Oppo is better when using it's internal DAC than it is when used as a transport with my external DAC.
Honestly, I'm frugal to a fault (ask my wife!). I typically only buy equipment when I know I can resell it for little/no loss. I took a chance on the mod'd Oppo and couldn't be happier. Absolutely no buyers remorse.
If you are near Cincinnati you are welcome to stop by for a listen. Otherwise, Ric does provide a money back policy if you send him a new unit for modding.
Ric is located near San Jose, Ca. He may be able to hook you up with someone in your area for a listen. He seems like a really nice guy, so it couldn't hurt to ask.
I do want to caution you that it is a consumer grade product as stated by Celtic. But if you are OK with that knowledge, it's a very good sounding player. If that concerns you, then buying an external DAC or dedicated CD player may make you more comfortable.
I spoke with Ric at EVS a while back after buying his DAC 1, which I still use, and at that point he was discontinuing his own DAC in favor of modding players because he thought he got better results (in line with what Flye said above). So there's that for what it's worth.
I'm also considering modding my Oppo 970 that I'm currently using as a transport only, but I can't get any of my interconnects to fit in the narrow space provided by the RCA input jacks -- a major limitation. Also, about a month after I had the unit the drawer stopped working and I had to send the unit to get fixed (the unit has worked fine since by the way). Great customer service and turnaround time, but I'd hesitate to send a new unit to Ric since modding probably voids the warranty. Just a thought and best of luck...