Optical Toslink vs.. RCA SP/DF cables best??

Hi. I recently introduced my old Denon DCD-3910 universal/DVD player to my dedicated 2-channel listening room to take advantage of its DVD-A and SACD playback capabilities. The Denon actually has 3 pretty good 24-bit Burr Brown audio DACs per channel internally, but I thought I'd use the digital inputs to my Cambridge Audio Azur 740C vII 96/384 hi rez CD player/DAC as an external DAC for the DVD-Audio digital signal. After extensive fiddling with the Denon's on-screen programming, I have the Denon set up for high-rez 2-channel audio analog & digital playback only. Thus I have the SACD signal converted by the Denon's internal DACs and output through the analog outs and directly into my Musical Fidelity preamp, and the DVD-Audio digital signal output through the Denon's digital outs through an optical cable into the Cambridge's optical digital input. The sound is very good, and it is interesting to compare the DVD-A signal through the Cambridge's external DACs vs. the analog SACD 2-channel signal through the Denon's internal DACs. Two important questions: Is the Toslink optical cable or the RCA cable best for a 1 meter trip from the Denon to the Cambridge? Second, some have told me that 2-channel high-rez DVD-A signals cannot be transitted through Toslink or RCA connections, but only through HDMI or I-Link connections. The Denon is clearly doing it. What gives? Thanks!
The rest of my system consists of:

Musical Fidelity A3cr dual-mono amplifier
Musical Fidelity A3cr dual-mono preamp
Perreaux MC phono preamp
Vintage Denon DP-47f turntable
Ortofon Samba low-output MC cartridge
Cambridge Audio Azur 740C vII CD player
TrippLite 2400 power conditioner/voltage regulator
Von Schweikert VR-4 loudspeakers
RBH external subwoofer amp
RBH VPS-12 passive sub
all high-quality interconnects
Hi KKing,

personally, i have found i prefer RCA outs for digital. As for DVD-A, i think some of the high-res formats are blocked for output thru non-hdmi because those outputs are not encoded (to protect against copying).

In your case, i [think] the signal coming thru may be downsampled 16/44. In my case, i can play an SACD from my Oppo Blu-Ray player digital out into my Zanden DAC...but i know that the player is reading the 16/44 layer.

Partly because Zanden does not accept SACD, and therefore any music coming thru it from an SACD must be the 16/44. The Oppo seems to do this automatically.
RCA SP/DF no question is better even with a lower costing digital cable .
I just had a surprise when I connected my music source to a Wyred 4 Sound DAC2 using an inexpensive, although of decent quality, TOSLINK connector and compared that to a Xindak RCA Digital cable. Switching back and forth, I found the TOSLINK to be slightly clearer and more realistic. Given all the hype on using RCA Digital cables and very little on TOSLINK today, I was not anticipating a quality improvement. I have just stopped listening to the Xindak Digital cable (which was selected over several digital cables in my system due to its superior sound quality) once I spent a couple of hours with the TOSLINK.

One great benefit of TOSLINK is that very good cables are much less costly than good RCA Digital cables. I just ordered an upgrade to my current TOSLINK cable from SILFLEX GLASS with 470 strands of glass fiber for less than $100.
Just received the SILFLEX GLASS with OPTISILK JACKETING to replace my previous no-name but good quality cable. I found the first couple of hours with the new cable was a disappointment. Sounded too much in your face at a very slight harshness.

After 5-10 hours it started to sound amazing. Toslink breakin? I didn't believe Toslink cables needed breakin - it's just photons passing through glass. I still don't believe it. I finally came up with the hypothesis that it is the internal W4S DAC2 optical to electrical interface that might have benefited from the breakin. Who knows, but it did improve dramatically over the first few hours of listening.

I wonder how many people like me who have stayed away from Toslink cable due to the bad reviews and negative comments. After listening to the Silflex cable I was blown away by the clarity and "sense of musicians in the room" feeling that you got on many recordings, especially vocals.

I have the RCA digital still connected for A/B comparison, and while it sounds good, it is more diffuse and without the sense of "musicians in the room" feeling that the Toslink cable provides.
Ronwills I agree I had the same experience using glass Toslink. It also removed some high frequencie glare that was present using RCA digital out.