It this a decent Phono setup?

Yes, decent…

Does it sound good to you? If so, then yes. 

It appears that you have a pretty well balance vinyl set up. Nothing stands out as a real weakness. If you want to invest a little then you could get a better cartridge.

Longer termed, my rule of thumb is that each component (carefully chosen to be the best in class and compatible with your system and taste) will usually cost about the same. So TT, Phonostage, preamp, amp, DAC, Streamer. This is a useful way of looking at the whole system.

Looking this way, your Mark Levinson sets the level at $3K / component ($3K preamp + $3K amp). Therefore to get the very most out of your system a $3K TT and $3K Phonostage would be optimal. So, if you wanted to look into the future there is room for growth in your vinyl end.

Just a real rough guide. But typically over the last fifty years of upgrades I tend to end up in these proportions + or - 25%.

Sell the Denon. Get a Technics SL1500 TT ($1800) and a Hana SL mc cartridge ($750). Way better sound quality than your present setup.