Do I really need a preamp with dac with volume control help

Ultra high end systems are not likely to exclude all popular media, and will therefore will probably have analog sources, which changes the equation.

Given your enjoying the system and it is working well for you, I would not bother. For high end critical systems not having a preamp seldom is a satisfying and fully fleshed out sound. But since it is a secondary system, I would leave it there. 
 

Leaves more money for your main system long termed.

Technically you might not NEED a preamp but I have never seen a top performing system that didn't have a quality preamp. 

It depends on the number of bits available from the DAC, the output voltage of the DAC, the input sensitivity of the amp, the capacitance of the interconnects between them, and the impedance compatibility of it all.

@paulcreed, There is no right or wrong answer to your direct to power amp, or preamp question. The answer is it depends on the equipment used and how it sounds to you. AND, if you ask everyone on Audiogon, you will get many different answers.

The only way to get the correct answer for you, and YOUR equipment, is to test and listen.

This is also something that I have wondered about.  I use an MSB Discrete DAC direct to my Pass Labs 250.8 and it sounds great.  Some have told me that putting a preamp in will improve the sound.  Others, like Vince Garbo at MSB, say no.  To me, it seems as if most designs try to minimize the amount of “stuff” in the signal path, i.e., the less in the signal path, the better the sound.  So it is counterintuitive to me that putting all of the wiring and electronics of a preamp into the signal path between the DAC and the amp would actually improve the sound.  How does that work, logically?

It can be very expensive to get a preamp that sounds as good as no preamp at all.  

A Benchmark LA4/PA4 is one to try out for "wire with gain" ($2500 - $3K). I also have a CODA 07x preamp (which I use more, better feature match) but my LA4 is the King. The CODA 07x is NOT wire with gain.

A Topping pre90 is another candidate for wire with gain. ($600). Read the review next month in Stereophile. I just sold mine.

"Do u need a preamp?"

Topping Pre90 + Ext90 Review - Pre-amp my Power-amp! (soundnews.net)

 

Save your money.  You do not need a Pre for your second room.  I just recently tried my Lampi Pacific DAC as a pre and cou0ld not believe how good the sound was without a Pre.  You can always add a Pre down the road if you are not happy.  

My DAC has the ESS Sabre volume control implementation and balanced out as well as my solid state amp. But my Tube pre does not support balanced. Some times I switch from the pre to the DAC direct via xlr.  I think it may sound a bit more analytical but I always find myself migrating back to the pre   I think I prefer the tube pre SS amp combo.  The pre is also where the phono stage be.

https://www.psaudio.com/askpaulvideo/is-a-preamp-better-than-no-preamp/

PreAmp do take a very good job,in fact, it is called magnifier,but we just do not use that word often,and we use preamp, and very easy to let people think the sound is just need amplifier. In fact,the sound signal need magnify and amplifier before going to speakers,

But why some one get good sound directly from DAC to amplifier? It is usually happen due to the DAC has the preamp function inside,and the company did not say it very clearly.

I'm afraid only you can answer that one in the end. Do remember you have an extra box and cables to listen to. I have a PC which doubles as my streamer and music storage system. This machine feeds straight into a PS Audio Direct Stream senior and I couldn't be happier, it is so clean and super detailed . I certainly don't miss a Pre Amp.

You are fine dac direct is usually more transparent