[Solarium]

I have HD598's paired with X-Fi Titanium HD sound card from my desktop. I will be connecting an amplifier (with preferably low output impedance) via the line-out jack of the TiHD. From here, I want to connect both my speakers as well as my HD598 to my amplifier and the ability to switch between the 2. What would be a good suggestion for me to able to do this?
 
So it goes like:
 
Titanium HD --> "line-out" RCA jack --> amplifier --> connects BOTH speakers (2.1) + headphones with the ability to toggle between the 2
 
I've been reading that Schiit Magni is a good pair for the TiHD, however it doesn't have the connection I need and I will have to unplug the speakers and connect the headphones and vice versa every time I switch. I also read that the Fiio E09K offers some sort of "pre-amp" that I really have trouble understanding, does it connect to speakers?

 

[jcx]

there is no "good" solution - you need separate amps since the headphones have >100x more sensitivity than full size loudspeakers
 
the 2.8 Vrms that gives 1 W into 8 Ohms for a loudspeaker of, say 90 (+/- 6?)  dB/W sensitivity rating, gives > 120 dB  from the HD598  headphone
 
some regular audio power amps for loudspeakers have(had?) headphone outputs which drive headphones with a internal resistive divider from the speaker output
 
but those speaker amps were likely designed before today's higher sensitivity, lower Z headphones and won't have a good level match - the DIN 120 Ohm headphone output "standard"
 is basically dead today
 
many integrated AV systems just use a cheap op amp for a completely separate internal headphone amp
 
the X-Fi HD has dedicated (and rollable) op amps for the headphone output - at the Senn 598 sensitivity of 112 db/V you could want moar peak SPL than the rated 1 V output of the card but 112 dB peak SPL isn't shabby
 
the main problem would if the card headphone out jack has a switch cutting line out with the headphone plugged in

 

[Solarium]

Any suggestions for opamps to use for TiHD + HD598 combo?
 
Also, if I'm looking at the Fiio E9/E09K, will this allow me to connect both my headphones and speakers through it (TiHD RCA output --> E9/E09K --> speaker + headphones). Is the E9/E09K the only amp within $100 price range that does this? Any other alternatives.
 
Also, will I see any noticeable benefit from amp on the HD598 at all? It's a sensitive headphone with low ohm's.
 
If I were to need an amp, and I were to decide between the Schiit Magni and the Objective2 (JDS Labs version), which would be a better fit with the HD598 + TiHD (Burr Brown DAC) combo?