One topic that comes up often in lessons is that of dynamics in ensembles, especially large ensembles. While in typical etudes the dynamics are pretty clear cut, dynamics in reality are a moving target that change greatly with the musical context.
Two sets of dynamics
Farkas must also have experienced this same conversation in multiple lessons. As a result, in The Art of French Horn Playing he discusses the topic of how dynamic markings really work and vary by musical context. Farkas wrote
Most students go through years of indecision before finally coming to the realization that in ensemble playing there are, in effect, two distinct types of dynamic marks. One set is for accompaniment passages, and the other is for solos. Piano in an accompaniment means just that—play softly. However, the same mark in a solo passage might require much more volume. A solo passage must carry, even though the dynamic mark indicates softness. Your first duty in playing a soft passage is to make it audible….
Although solo passages can often be a degree louder than the dynamic indicated, the opposite is true of accompaniment dynamics. Here it is our duty to keep down sufficiently to let the soloist come through even though it means playing piano when mezzoforte is indicated. Thus the orchestral player might make a simple rule for observing dynamics. Solos should be played a little louder than indicated and accompaniments slightly softer
How about Brahms 3?
A really huge thing you have to think about is if music is melodic or back in the texture. One of my favorite excerpts that can show this awareness is Brahms 3.
There’s actually a very large difference between the dynamic of the first two notes. The first note is inside a woodwind chord and is not loud at all. The rest of it, there is a lot of sound on the stage and you need to overcome that and project to the back row! The first note is softer than printed, and the rest of it a good bit louder than printed.
It’s a moving target
So while Farkas is correct that there are two sets of dynamics, really it’s a moving target based on the actual context and texture. But speaking generally, if you think about people needing to hear this line or not, is it melodic or not, you will be close to correct.
