MC Phono Pre Gain

It is tied to the output of the cartridge you choose to use.
Low output carts need more gain than high output cartridges

At 0.15 mV that is pretty low output, even by LOMC standards. So you would likely want a fairly high gain phono preamp. I'd be worried about a phono pre with gain below 60dB (and even low 60s may be a touch problematic in certain set-ups).

BUT, this will also depend on the gain structure of the rest of your system. Where are you generally playing on your volume control dial? If you are between 7-10 o'clock on that dial and being higher on your dial doesn't introduce unwanted noise, then you might be able to get away with a lower gain phono pre.

I will let folks with experience with the DLS1 chime in on their recs.

I second Roscoeiii's response. With an output of 0.15 mV, you'd need about 67 dB of gain from your phono pre, give or take a few dB depending on the gain of your line pre. That is a lot to ask of the phono stage, and noise does become an issue with lesser designs.

For .15mv you need something that has a lot of gain and is very clean. My first choice would most likely be an Ayre 5 series phono preamp. Its dead silent and it sounds great. The Ayre is good enough that you probably will never have to upgrade.

Use the KAB gain calculator to determine total gain and then look at how much gain you have in your line stage and amp, your room size and the noise floor. You also need to consider what velocity the Denon's output was measured at; some carts like ZYX are measured differently than typical and thus their output SEEMS lower that it really is.