I will share my thoughts, albeit biased, but I do know the designs better than anybody else!
First of all, the Marantz is a CD/SACD player with no video of course.
Both mods use a tube analog stage and outboard power supply.
The 105/105D uses a tube regulated and tube rectified supply and 6SN7 as the driver tube. As such, it is a warmer, more laid back and has a more vintage tube sound!
The Marantz uses the 5687 tube in a different circuit with a tube rectified and SS regulated external supply. It is more neutral, resolving, detailed and dynamic. Still very much a tube sound, but not as warm as the Oppo 105/105D mod.
The latest player that we are modifying, that I am MOST excited about right now, is the Pioneer LX-500 Universal Player.
It plays all disc formats and does have a USB input for playing files from a static USB drive or thumb drive, but does not have a computer USB input. I.e. no network streaming or connecting to a computer, server or bridge. It requires a monitor of some sort to access the files on the external drive.
Because of the amount of space available inside the LX-500, we are able to install TWO new power supplies inside the player for a true one-box solution! It is also $1K less cost!
The stock player retails for about $995 and our mod cost is $1500 (vs. $2500 for Oppo and Marantz mods). The lack of external supply, PS enclosure and umbilical reduce our costs significantly! It also allows for a more convenient one-box solution!
I came across this player in a quest to find something to replace the Oppo 205 Universal Player when we learned that Oppo had closed their doors:
First of all, it uses the AKM DAC, which I find to be more musical overall than the SABRE DAC, and that is saying A LOT!
Secondly, Pioneer has done a FANTASTIC job of designing an enclosure and drive, that is very inert and resonant free! This is huge in terms of video and audio performance! The drive itself is encased in a completely damped and vibration free sub-enclosure. The overall chassis has a thick steel plate that adds significant rigidity and mass damping to the overall enclosure and other aspects of the chassis have all been designed to make this a sturdy and rock solid player! Very uncommon at this price!
Now they cut corners on the power supply and the stock analog stage. That is where we come in! The DAC is very good, but the power supplies supporting the DAC and poor quality op-amp based analog stage are built to a price-point.
We install two new power transformers and power supplies. One is low voltage and powers all of the audio digital circuitry. The second is high voltage and powers the audio circuitry. The stock power supply is a SMPS (Switched mod supply) and while this is fine for video, it is never good for audio. So we completely power the DAC, digital circuitry and our new analog stage from our own power supplies.
We then take the signal right off the DC pins, transformer coupled to our own Class A, zero feedback tube circuit, providing an extremely low output impedance, excellent bandwidth and very low noise and distortion!
Sonically, the player has weight and definition, body and an organic musical presentation that meets or exceeds that of our best modified players to date! We used two of these at Axpona this year, in a $30K system and a $130K system and it served both VERY well! In fact, it was the first time that I felt that our digital nearly rivaled our analog playback!
So, I am writing to answer the question about the difference between the Oppo 105 and Marantz, but also to let you all know just HOW GOOD the Pioneer LX-500 mod is! I feel that it is our BEST offering!