2 for 1 or the PS Audio upgrade route?

Choosing between upgrading to a single box solution or going for the PS Audio upgrade path ultimately depends on your personal preferences and priorities. Here are some factors to consider:

1. Sound quality: Both the Accuphase DP-720/750 and the Marantz SA-10 are highly regarded for their sound quality. However, sound quality can be subjective, so it’s important to listen to both options and see which one appeals to you more.

2. Future serviceability: It’s important to choose a unit that will be serviceable in the future, especially if you plan on keeping it for a long time. Accuphase has a reputation for excellent build quality and long-term reliability, and they offer worldwide support. Marantz also has a good reputation for reliability and offers local service centers in many countries. PS Audio also has a good reputation for customer service and offers upgrade paths for their products.

3. Upgrade path: If you choose to stick with PS Audio, their upgrade path may be an attractive option for you. However, keep in mind that upgrading to a single box solution may not be possible with PS Audio, as they do not currently offer a single box solution that combines the functions of the DMP and Directstream MK1.

4. Price: The Accuphase DP-720/750 and Marantz SA-10 are both relatively expensive, so price may be a factor in your decision. Keep in mind that PS Audio also offers high-end products at a range of price points, so you may be able to find a PS Audio product that meets your budget. Subarunet

Ultimately, the best choice for you will depend on your personal preferences and priorities. It’s important to listen to both options if possible, and consider factors such as sound quality, future serviceability, upgrade path, and price.

@jamesgoff writes a pretty comprehensive post above.  I will therefore address a peripheral issue.  The OP seems determined to be a 1 box solution.  Do SACDs and Blu Ray figure in the equation here?

SACD, I suppose, is required. Currently own 2 or 3 of them. Listen to them once or twice a year. It’s tough to lay down 20$ and up for one SACD when cds are essentially being given away for pennies on the dollar. 

If you're looking to upgrade from your PS Audio DMP and Directstream MK1 to a single box solution, there are a few options to consider. The Accuphase DP-720 or 750 and the Marantz SA-10 are both solid choices with excellent sound quality.

The Accuphase units are known for their high build quality and reliability, although they may be more expensive in the USA. The Marantz SA-10 is also a well-regarded unit with excellent sound quality and a more affordable price point.

Ultimately, the decision between upgrading to a single box solution or sticking with the PS Audio gear and upgrading over time will depend on your personal preferences and budget. If you're happy with the sound of your PS Audio gear and appreciate the ease of upgrading over time, then sticking with the PS Audio upgrade path may be the better option. However, if you're looking for a single box solution with superior sound quality, then the Accuphase or Marantz units could be the way to go.