That's a difficult question. As far as I know we don't have much to work with in terms of sources (stuff this old is way out of my league).

There's a mention of some kind of war-song in Tacitus' Germania:

III

They narrate of Hercules’ erstwhile stay With them and sing to him before the fray To him number one hero among the strong.

They also have many a ‘baritus’ song auguring the impending battle’s fate With notes possessing a rhythmic clout kindling their souls as they’re belted out And according as their bands resonate Scare their foes while they themselves trepidate As more than voices they have the illusion Of hearing of valour the warlike fusion Both harshness and asperity Along with a broken clamour Are sought out particularly With mouths and tongues lambent To the shields of the armour So that harder and louder may boom The reverberating voice of doom

Ammianus Marcellinus also mentions something that might have been some kind of war-song war-cry (that the Romans didn't like):

XXXI.7.11

Therefore when the armies on both sides, advancing more cautiously, at last halted and stood immovable, the warriors, with mutual sternness, surveying each other with fierce looks. The Romans in every part of their line sang warlike songs, with a voice rising from a lower to a higher key, which they call barritus, and so encouraged themselves to gallant exertions. But the barbarians, with dissonant clamour, shouted out the praises of their ancestors, and amid their various discordant cries, tried occasional light skirmishes.

Jordanes also talks about music (maybe about the Goths) in his Getica:

V.43

They were the first race of men to string the bow with cords, as Lucan, who is more of a historian than a poet, affirms: "They string Armenian bows with Getic cords." In earliest times they sang of the deeds of their ancestors in strains of song accompanied by the cithara; chanting of Eterpamara, Hanala, Fritigern, Vidigoia and others whose fame among them is great; such heroes as admiring antiquity scarce proclaims its own to be.

I guess those are not terribly useful to really know about Germanic music...

Getting a little closer to the Holy Roman Empire, we find the so called Carolingian Renaissance. By that time, the chant of the Church in Rome was migrating north.

Charlemagne invited Albinus of York (an English scholar) around 781 to set up a cathedral school. The curriculum was that of the trivium and quadrivium, this last one including music. Now, by music I mean mostly some ancient Greek theory (which includes the maths to determine musical notes by using ratios and lengths on a taut string).

It was decided to unify the liturgy of all the realm (which was quite big). This meant the previous forms of chant (including Gallican chant) had to go. It was not an easy process, and this effort of standardization was significant for the history of music because we see the Western musical notation appearing during/after that process.

Do we have any concrete German musical examples from before the HRE? I am not sure. Well, I think it's closer to "no, not really" but "kind of" if you are not too picky.

The Planctus (de obitu) Karoli is an anonymous eulogy written close to the death of Charlemagne (so this might be a little more "French" than "German"). We have music associated with it, but the notation (which is one of the earliest kinds we have) is not from the time the text was written. I cannot tell if the music was composed much later, or if it was communicated via oral tradition and then notated. In any case, here's a video. Compare the previous recording to this one, or even to this other.

That notation is very problematic. You see the text, and then some neumes (dots and squiggles) above it. Those are not very specific... Be very sceptic about recordings of this sort of music. Yes, a lot of knowledgeable people have worked hard to get an idea of what all that sounded like, but the information we have is very limited. Some speculation is needed to attempt to recreate pretty much all music earlier than the 19th century, attempting to recreate music from neumes obviously requires MUCH more.

We have every reason to believe there was non-liturgical, non-religious music, and that there could be music with more instruments than the voice (with more instruments playing at once, too). However, I don't know of any surviving example of such music.

TL;DR

As with most music from so long ago, not terribly much. You are asking about something that is kind of prehistoric, because Western musical notation started to develop about the time limit you set.