Anthem STR "Convert Analog" sounds much worse

It might help if you read the manual.

The bass manager divides the audio range into two bands suitable for subwoofer/satellite speaker systems. The result is
that the main speakers don’t need to play bass as loudly or as deeply since it gets picked up by the subwoofer. Note that a
crossover does not suddenly cut frequencies in a cliff-like profile, but rolls them off according to a slope. If set to 80 Hz, for
example, frequencies lower than 80 Hz are still played by the main speaker while transitioning them to the subwoofer.

The range is 25 to 160 Hz in 5 Hz steps, or Off which disables the crossover.
Setting the crossover to the lowest number on your speaker’s specification page is unlikely to provide the best result.
Instead, setting it to twice this frequency or thereabout, which is an octave higher, ensures that the speaker’s woofer will still
play to its low frequency limit but at levels that present less of a struggle for it.
If you will be using the personal computer version of ARC, you do not need to select the crossover frequency since it will be
set while running the program.

I thought setting the crossover in the Anthem created a high pass or low pass whatever for the mains... i.e. setting the xover at 50hz sends nothing below 50hz to my main speakers.. No? So using the subwoofer management on my Anthem still sends full range to my speakers?

It is adjustable. You can set the HP filter on the mains (which ARC calls "Subwoofer Crossover Frequency") to FLAT if you like. That will run the mains full-range.

I suggest you try letting ARC set everything automatically before you do that, though. You can save that calibration file, then copy it to another name, re-open it, and adjust ARC settings ("Adjust Targets" for each of the four allowable profiles. That will let you compare easily.

To get access to all the adjustments, you need to run ARC on a computer (not a mobile phone) and in Professional mode.

As others have said, you will get better sound using a digital input on the STR, rather than converting to analog in the Lumin, converting back to digital in the STR, then using the STR’s DAC again to get analog output.

After you have a correction set up, be sure to run the automatic phase feature, which will give you the most even LF response for several octaves around the crossover area. Without it, you are likely to have nulls and peaks.

Many settings in ARC can affect the sound in ways you might not expect at first. For example, speaker levels have no effect if you are running corrections full-range. But if you’re not, they affect the relative levels of response within the correction bandwidth and outside it. Thus, a click or two change in levels can change brightness of the sound.

It will take some playing around with ARC and thought about what it’s doing for you to fully master it. Also (as has been said in many reviews of DSP products) if a listener is used to hearing bass peaks, it can take a while to adapt to sound without them.

HTH

Thanks for all the input. Im going to play around more.  

So it looks like, if I want to use subs, I wasted alot of money on the Lumin T2 and should have just gone the streamer route since I have to filter everything through the anthem's processing anyway.

Yes,  DSP is digital signal processing so it's done in the digital realm of the Anthem. All you needed was a basic streamer. In order to get the best of what DSP can do is run the subs through it with the main speakers. You will be able to keep the bass of the mains the subs will augment them. As Mike pointed out it will probably sound different until you get used to what bass should be like without peaks and nulls and the God awful boom. 

In an act of humility and embarrassment, I have a confession.  I had the input levels for XLR -5db which is activated when "Audio Convert" is turned on....  

Now, when I switch between the two, there's no audible difference that I can tell at this point.. Mayyybbeee on some parts of some tracks there might be a difference but rarely is a change/tweak noticable or even "better" over the whole spectrum.

Apologies for being an idiot.  Sometimes settings get buried deep down in the menu and you don't know what you've changed...