The Fiddle and Friends

You might have expected 'one each of each' in the four sizes of the modern violin family, but there are two violins instead and no contrabass. The range of pitches is typically within the range of the human voice (from baritone to soprano, or above that in more extreme violin passages) which may be one of the elements in this medium that appeals to players and listeners, since the music proceeds in ways analagous to conversation or debate

Answers 1-3 are all techniques in the preparation or playing of a stringed instrument, but 'purfling' is a feature of the decoration of the bodywork of the instrument

It has four 'conventional' strings, and another four set beneath them which pick up and enrich the vibration of these main strings. Other instruments from elsewhere in the world may have similar strings; this is not limited to the Hardangerfjord in Norway. Even there, however, this fiddle may have its strings tuned in any one of 20 different schemes, a little like the ukelele

This phrase means 'with wood'. The brittle, spiky sound is almost other-worldly, reminiscent perhaps of the jagged barbed wire and ruined trees and buildings of the Great War which began while Holst was writing the piece.
Your present author is old enough to remember hearing this piece as his first-ever digitally recorded track from a CD, rather than the previous analogue / vinyl versions, and can attest that for the first time in his life he could 'hear the texture of the wood'

The concert harp has 7 pedals, each engineered to raise or lower notes of the same pitch-name throughout the instrument's range (e.g. B) by one semitone. So far as we know, this is the only instrument where the player's feet are used to change the pitch in such a way; a pianist's feet add expressive and 'textural' elements to the interpretation, and organists and pedal-harpsichordists routinely play notes with their feet

His lute songs are early classics of the genre

There are about 650 known/acknowledged 'Strad' instruments in the world today

Traditional strings are/were often referred to as 'cat-gut' (as with the stringing of tennis rackets) but would far more usually be made from the gut of a sheep (any one 'head' of which would obviously yield a lot more gut than one small cat). The horse's involvement is limited to a couple of hundred tail hairs with which to 'string' each bow.
We cannot readily imagine how the products of any of these other mentioned species might have contributed to such a performance!

This is indeed the Zither, whose roots may go back into Old Testament times. The word itself is fairly distantly related to 'guitar': well, we suppose they may both be played by strumming or picking.
The Zymbelstern (Answer 1) is, if anything, a percussion instrument: it is in the shape (usually) of a smallish revolving star, mounted on the top of the case of a large pipe organ, and when engaged this star revolves gently so that a series of little chimes is sounded, slightly akin to a vertical version of the 'angel chimes' that some people may have on their meal table or elsewhere around Christmas time. All very charming and tinkly if you happen to like that kind of thing!

How better to round off this Quiz than with the beaming performer (concertist, leader, whatever) taking due credit?