The description of Nexus says that the spell has a reduced effect when less people are around:

>>A simple spell in concept, if not execution, Nexus stirs the elements to create a localized wellspring of mana. When cast, this spell creates a connection of sorts between those around you and the elemental plane. A wonderful by-product of this relation is the blending of musical tones, becoming more robust in sound and potency of effect with each additional person nearby to feed into the spell. If used alone, its effects are far reduced.

Is this actually working, though? I've tried it by myself and a room with 14 people in it and get the same improvement. I'm only casting it with 40 mana at this point, so is the improvement so small that it's not noticeable for most bards?

Mana levels before:
You reach out with your senses and hear lambent (12/21) streams of harmonious Elemental mana coursing through the area.
Concentrating harder on the sounds you hear, you can sense glowing mana below you, flickering (8/21) mana to the west, pale (7/21) mana to the east, and glowing (11/21) mana to the northeast.

Mana levels after, with 14 people in the room:
You gesture.
Your cambrinth armband emits a loud snap as it discharges all its power to aid your spell.
A gently glittering series of colored lights appear in the air, winking in and out of existence around you, as the sound of a lone flute begins an ethereal melody.

>conc
You reach out with your senses and hear shining (13/21) streams of harmonious Elemental mana coursing through the area.
Concentrating harder on the sounds you hear, you can sense glowing mana below you, flickering (8/21) mana to the west, pale (7/21) mana to the east, and glowing (11/21) mana to the northeast.

Mana level with just one other person in the same room:
You gesture.
Your cambrinth armband emits a loud snap as it discharges all its power to aid your spell.
A gently glittering series of colored lights appear in the air, winking in and out of existence around you, as the sound of a lone flute begins an ethereal melody.

>conc
You reach out with your senses and hear shining (13/21) streams of harmonious Elemental mana coursing through the area.
Concentrating harder on the sounds you hear, you can sense glowing mana below you, flickering (8/21) mana to the west, pale (7/21) mana to the east, and glowing (11/21) mana to the northeast.

Not in a position to check the multiple people thing, but it gets better at higher mana.

Before Nexus:

You reach out with your senses and hear radiant (15/21) streams of harmonious Elemental mana coursing through the area.
Concentrating harder on the sounds you hear, you can sense brilliant mana to the southwest, and brilliant mana to the east.
You sense the Minor Physical Protection spell upon you, which will last for about thirty-one roisaen.
You sense the Harmony spell upon you, which will last for about six roisaen.
Roundtime: 3 sec.


100 mana Nexus, alone in room:

You reach out with your senses and hear glaring (19/21) streams of harmonious Elemental mana coursing through the area.
Concentrating harder on the sounds you hear, you can sense brilliant mana to the southwest, and brilliant mana to the east.
You sense the Minor Physical Protection spell upon you, which will last for about thirty roisaen.
You sense the Harmony spell upon you, which will last for about five roisaen.
You sense the Nexus spell matrix in the area, which will last for about thirty-nine roisaen.
Roundtime: 3 sec.