Preamplifier options - seeking help to determine which one

Can I ask what drives you to these products? Are you aware you can buy some pretty good proven equipment in this price range that are better know in the hifi world than these pieces. Not saying they're bad, but I'm not sure anyone can really say anything about this brand. However, if you asked for recommendations in this price range you'll get a lot of responses.

Sure. I have been investigating possible options for tube-based amplifier for quite some time and after studying extensively I have come to the conclusion that I prefer Japanese brands due to their values and philosophy of audio reproduction. Shindo (which probably is better known) is not easy to buy anymore. Audio Note Kondo is too expensive for me. There are a lot of other brands but I have heard so many great things about Yamamoto. 

Regarding CA-03, I'm assuming the attenuator version doesn't add any gain, so it's cleaner sounding with better signal-to-noise ratio. If you tend to listen mostly at low volume then this version would be great. But if you like to pump it up at times, you might want to go with volume version, which I'm sure would sound pretty amazing too.

Either version of CA-03 will work with you Denon DL-103R. No need for a SUT. Just set the back switch to 100 ohms.

You are correct, CA-04 is just line-level preamp without the phono stage. You would need an external phono preamp with this choice. SUTs only bring low MC signals up to phono level NOT line level. They cannot work by plugging them into line-level inputs. SUTs need to be plugged into "phono" inputs. That said, if you do buy an external phono stage make sure it can accept MC cartridges or you will have to also buy a SUT.

Yes, you can plug the Airport into the AUX on the new preamp, just as you use the AUX on the Sansui.

Thank you very much for your explanation. I primarily listen to jazz and classical music - everything from solo pieces to larger ensembles and orchestral works. I live in an apartment and I do not listen to extremely loud levels - I'm not hosting techno parties and desire a crazy subwoofer that shakes the floor. Rather I like an emotional and intimate listening experience with a natural soundstage with lots of depth. Sometimes intimacy can be acquired when you turn the volume up a bit and the music embraces you, but I wouldn't say that I listen to very loud music. 

My understanding is that the double volume level item makes me control the volume of each speaker which can be preferable if your room requires it. I'm not so sure what the attentunator does. 

A follow up question: How come there are so much difference in the price between the two? It seems that CA-03 is the superior model, is that correct?

The Yamamoto tube is beautiful... And i trust japan audiophile engineer...

i cannot help you with your choice...

But Yamamoto seems a good choice...

My speakers are powered and a pre-amp with tube in my case and a equalizer made a world difference... but i am not on this price level...

Came back here once your choice is made and gave us a review...

I wish you the best...