parallel second or third stage?

[azatplayer]

I see a lot of amps using parallel input stages. Just wondering if the reasoning still stands further away from the input? Im thinking typically on a three gain stage amp where theres a spare triode. Using at the front is normal procedure.
Are there any benefits or pitfalls to using it later?

[surfsup]

I would think it is used at the input more because that stage get amplified the most and the benefits there are greater. After, the extra gain is not really necessary since you can start clipping the stage with out it being paralleled usually, yes?

I would think it would be a better use of a triode to put in a cathode follower instead to boost up the even order harmonics? Though I'm still unsure in a PP if the PA cancels even order generated in the PA or any opposing even order harmonics from the PreA.

I was kinda wondering what to use a single stage later on for myself and would appreciate some commentary from someone that knows what the heck they are talking about (not me).

[FYL]

Are there any benefits or pitfalls to using it later?

Using // sections gives more gain (around 30 %, depending on the actual tubes used) with twice the transconductance (more dynamic response, better touch sensitivity) as well as lower noise and doubled current swing. Purrfect for a front end, but not useful in most other sections.

[Gibsonman63]

By adjusting plate and cathode resistance you could get the same gain as a non-paralleled stage using standard values. Would it make sense if you were building a 4-stage gain monster to have a second or even a third section with lower noise?

[tubeswell]

What FYL said plus, using a || stage also halves the stage's plate resistance (rp), so (depending on the value of the plate resistor (Rp) selected) that may be useful in reducing output impedance in order to drive a bigger AC load (like more lossy tone stack) better.