DL-103 + A23 SUT + Pro-Ject Tube Box DS = ?

I will say it again:

This is the worst tonearm for Denon DL-103 low compliance cartridge. 
I have no idea why people brainwashed so hard, but Denon is NOT good for modern turntables/tonearms, because it was designed in the era where HIGH MASS tonearms were normal (it was designed in the late 60s). Today nearly all tonearms are mid mass, but Denon compliance is extremely low even for mid mass tonearms. Do you what does it mean ?  ** Here is the article. *** 

If you want to use your Denon in a proper way you need a super heavy tonearm, something like FR-64s, but definitely NOT a Pioneer tonearm. 

Your Pioneer is great for vintage MM/MI cartridges, they are superior to Denon 103 in everything and you don't need such expensive SUT at all (you can buy better cartridge instead). 

Why in 2020 you need a cartridge from 1969 with Conical tip ?
Can you explain ? Who told you this is the right choice for Pioneer ? 

It's so easy to search for a proper tonearm for Denon 103 and SPU, they are all high mass tonearms by default. 

I don’t care about Stereophile recommended componets and their reviews at all, but I know very well that low compliance cartridges from the late 60’s designed for high mass tonearms. Also I know that DL-103 designed for broadcast radio stations with its conical tip.

I like Zu Audio speakers and cables, but their MOD of the stock DL-103 will not make this cartridge any better, because the problem if this cartridge is its Conical Tip (rolled-off sound, very short life span).

Those guys at Stereophile can’t recommend Pioneer PC-1000 mkII cartridge, because they know nothing about it, but it was the best Pioneer MM cartridge in the 70’s and far better than Denon DL-103 from the 60’s.

In fact ZU recommended you exactly what they are selling.
And Stereophile do not recommend anything that not available for sale in the stores today, but all those modern MM cartridges are junk compared to vintage MM from the 70s/80s. If in Stereophile expert’s opinion a DL-103 is better than modern MM cartridges it is nothing but a confirmation how bad those modern MM really are. Because DL-103 is nothing special, just a cheap LOMC.