Why a passive pre amp?

Since the goal is input selection with attenuation... passive is better.

The catch is that the source needs to be pretty beefy since its now the last amp stage before the amp and likewise the amp should be relatively sensitive.

Weak source with insensitive amp will cripple a passive preamp system as far as volume output. I like the Adcom and CI Audio passive pres. The CI is a real bargain that my parents use in their Classe stereo rig since their active pre went up in smoke. Other than looking a little dinky, if you only need 2 inputs its quite good.

I m also interested in knowing which of active or passive preamp alters the sound the most (May sound stupid, I m guessing active but you never know), and wether anybody know where I can get a correct one with a Remote :d

The Melos has a passive pre-out and an active out with a tube gain stage. The passive goes out to the Marantz because I think a nice clean signal is best for that vintage beast, and the tube active out goes to the STAX because it helps beef it up - it's like putting a tube gain stage in there so the SRM-1/MKII changes from a pure Solid State into a Tube Hybrid, hehe. Just fyi, the Melos' headphone out is connected to the Tube Active Out as well, which helps contribute to its non-anemic nature.

if the sole purpose of your preamp is source selection.. then a well designed passive circuit would be better, in that theres minimal coloration and "artifacts" that poorly designed active circuits generally tend to introduce.

If the intent of your preamp is to color the sound (bass boost, crossfeed...etc...) then a passive might not be your best option.

There are different types and quality of "passives" just like different grades of active preamps. One can't lump them all in one b/c I've certainly heard passives that don't sound great, especially ones using poor-quality or long wires internally, poor volume control, witches, jacks, etc.

I've auditioned/owned many passives, including Bent Audio silver TVC (transformer volume control), simple DIY box with high-quality volume pot, Placette passive preamp, Endler passive attentuators, EVS Ultimate Attenuators, EVS "Nude" Ultimate attentuators, etc.

With all passives, even TVC, a "sympathetic" environment is needed for them to strut their substantial benefits. You need sources with stiff output stage and low output impedance, cables with low capacitance, amp with high input impedance, speakers with high sensitivity, or some combo of above that'll work well.

If such setup is achieved, my favorite remains EVS "Nude" Ultimate attentuators, which has an advantage over passive "boxes" b/c it bypasses an extra set of interconnects, connector jacks, internal wiring, etc.

To match or surpass the results of something like that in a synergistic system, one will require an active preamp of exquisite quality, usually very expensive. I'm talking about the likes of Aesthetix Callisto Signature preamp ($11,000), VAC Renaissance Signature pre, etc.