Yes but neither do the caps sound like a typical plastic cap either and why offered as a choice.
The goal is to avoid the plastic sound,to have gobs of detail and yet have that detail spread evenly across the board rather than to one or a group of frequencies which if in the mid to upper registers is death to any headphones or loudspeakers that already have a large amount of energy in that area (rather than the intentional sugar coating of most drivers
)
This also goes to topology and usually hand in hand with class-A operation be it single ended or push-pull with each part having a role to play in the overall balance of the final presentation.
For instance :
A single paper in oil cap at the input of a solid state amp or amps using certain triodes (6C45 comes to mind) can usually make the entire amp sound better,maybe even make a formerly unlistenable amp a keeper but put that same cap at the front end of a DHT SET amp or a Single Ended Class-A MOSFET amp and you may find the sonics are a bit too "polite" for the recreation of the dynamic sound of live music.
all the circuits above are capable (assuming a sound design) and all the parts are quality ones yet some just don't play well together while others seem made for each other and this is a thing no specs,no scope trace and no follow the leader parts upgrades tell you.
If there is a constant with me it is that I try to
mostly avoid all plastic caps and metal film resistors in the signal path because they for me have a cold/sterile sonic profile and my opinion is music is anything but.
That does not mean I avoid ALL plastic and ALL metal film resistor use but that I pick my spots and that comes with living with a design first to identify any weaknesses then setting out to rectify them hopefully.
For example-my Meier Audio Cross-1 passive crossfeed network.I used Holco metal film resistors at the bass and treble trim stages but NOS carbon comps and "plastic" 715 Orange Drop caps in the filter section and it works.Yes the Orange drops can be microphonic and yes they can be a bit "blurred" in the detail area but in this instance it works
in my system.
Mundorf Supremes,Jupiter Caps,PIO-all detailed and all sound good but each sounds
different and is a perfect example of why the hardest part of designing any audio circuit is not the topology but doing the parts identification stage.It is the details that make or break a design and why I always found it comical when so many would shit on the Grado RA-1 amp as "just a simpe opamp,nothing special" without ever realising someone had to spend the hours determining exactly what cap and what resistors would work well with the combination of the opamp and Grado cans because there is in this case an actual targeted end use.
The fact that a simple cap coupled low gain "opamp in a box" works as well as it does with the intended end use headphones means someone listened but that listening no doubt took many man hours on the bench before the combinations were locked in while the know nothings toss whatever cap or resistor is currently popular (read in use in whatever project is popular at the time) at every single audio project.
This shotgun approach to parts upgrading will never make a toally satisfying project unless totally by accident.Pure dumb luck and no.No way you can make a thing better if you have no idea what that
thing even sounds like so many times these upgrades are no more than "wallet downgrades" and can in fact make for a very nasty sonic profile when every pole uses the same cap (pole as in filter which a cap is ) and all points of resistance/voltage division use the same same resistor type.
may look cool on the pcb when everything is color co-ordinated,layed out in pretty rows and looks good enough to eat but should be the last choice in method if the sonics are your main priority.........and they should be.Pick the part to suit the job and that only after you know what you have.For amp designers it is part of the design processs so no thought required.For modders or kit builders you need to listen,identify what you do and do not like,what parts you would better then set out to accomplish it with a planned assault that has an actual goal other than "pretty" parts
.