Plutarch On Music 5 :

Alexander in his Collections on Phrygia declares that instrumental music was introduced into Greece by Olympus and by the Idaean Dactyls or Priests of Cybelè. The first flute-player according to him was Hyagnis, who was followed by his son Marsyas, who was succeeded by Olympus.

Ibid. 7 :

[on lyre-sung “nomes”]: We are told that the Olympus of whom we spoke just now, a flute-player from Phrygia, composed a flute-nome3 to Apollo which is known as the Many-Headed. This Olympus, however, is said by some authorities to have been a descendant of the first Olympus, son of Marsyas, who composed nomes to the Gods. – This earlier Olympus was in his boyhood a favourite of Marsyas, and learning flute-playing of him, introduced the musical nomes3 into Greece, where they are now used at the festivals of the Gods. – According to another account, however, the Many-Headed nome is the work of Crates “a pupil of Olympus” though Pratinas declares it to be the work of Olympus the Second. The Harmatian nome, as it is called, is reputed the work of the first Olympus, the pupil of Marsyas . . . and this view is supported by Glaucus in his Account of the Ancient Poets . . . It is held, however, by some writers that the Harmatian nome was a Mysian invention, Mysia having produced flute-players in ancient times.

Ibid. 11 :

According to Arisoxenus, musicians ascribe the invention of the Enharmonic scale (EE’FABB’CE)4 to Olympus. Before his time the only scales had been the Diatonic and the Chromatic. The invention is supposed to have come about thus: In descending in the Diatonic scale his melody frequently passed from B or from A to F, omitting G. Realising the beauty of this effect, Olympus in his astonishment accepted the principle for the whole system, and composed in it in the Dorian “mode,” rejecting all intervals peculiar to the Diatonic or Chromatic scales and concerning himself directly with the mode. Such was the origin of his Enharmonic scale . . . It is clear that Olympus made a real advance in music by introducing an entire novelty, and was the father of good music in Greece.

Ibid. 15 :

We are told by Aristoxenus in the first Book of his Treatise on Music that the first flute-player to use the Lydian mode was Olympus in his Lament for the serpent Python.

Ibid. 29 :

The Olympus who is reputed the originator of art-music in Greece, is considered to have invented not only the Enharmonic scale but the two rhythms known as the Prosodiac which is that of the Nome of Ares, and the Choree which occurs so frequently in the tunes used in the worship of Cybelè. The Bacchius also is sometimes ascribed to him.5 These statements are borne out by each of the ancient melodes.

Ibid. 33 :

Take for instance the Enharmonic scale employed by Olympus with the Phrygian mode and the Epibatic Paeon,6 the combination which gives its character to the opening of the Nome to Athena. Both melody and rhythm make their contribution, the metre being merely changed in a cunning way so as to become as it were trochaic instead of paeonic, and the effect is completed by the use of the Enharmonic scale of Olympus.

Ibid. 18 :

Moreover, although the ancient poets used only some of the “modes,” they knew them all. It is not through ignorance that they confine themselves to employing so few strings,7 or that composers like Olympus and Terpander and their followers denied themselves the use of many strings and the variety which that entails. This is clear both from the works of Olympus and Terpander and those of the composers who belong to the same school. Though they are quite simple and written only for a few strings, they so far excel the elaborate works written for many, that the style of Olympus remains inimitable and the exponents of the opposite principle have to take the second place.

Aristotle Politics 8. 5 :

[on music]: This would be clear if we could show that music affects our characters. And we can, by many instances, notably that of the musical compositions of Olympus, which admittedly carry us away, an effect which is a condition of the character of the soul.

Suidas Lexicon :

Olympus: A Phrygian, the younger of the name, a flute-player who flourished in the time of Midas8 son of Gordias.

Hesychius Glossary :

Nome of Olympus: One of the composers for the flute.

Aristophanes Knights 7 :

Demosthenes. My poor old mate, how d‎’ye feel?
Nicias. Bad, as bad as you do.
Dem. Then come here, and “let’s pipe Olympus’ nome of woe in concert.” [They hum a few bars.]
Scholiast on passage:
Olympus was a musician, a pupil of Marsyas. He wrote dirge-nomes for the flute.

2. In ancient times there was come confusion between the elder and younger musicians of this name. Both seem to have been musicians pure and simple, but are included here because the development of Greek lyric poetry is hardly separable in its early stages from that of Greek music
3. i.e. a certain type of air for the flute alone, not for flute and voice as above
4. the dash indicates a quarter-tone
5. see also Plut. Mus. 10 (on Thaletas)
6. perhaps the “3rd Paeon” called dromios or “running”
7. or “notes”; the Greek word is intended to include the stops of the flute; so also below
8. died B.C. 693