It's interesting (as Dave's last posting illustrates) that euphonium players tend to think of finding "the horn", while conceding that some horns are better than others for some contexts and applications. This contrasts rather sharply with the typical tuba player (at least at a high amateur or professional level), who is not only willing, but anxious to possess at least a couple of horns for different uses -- typically a "large" CC or BBb contra-bass tuba and then a smaller (usually F, but sometimes Eb) bass tuba for uses in smaller groups, quintets, etc. It also contrasts with many trombone players who have at least a tenor of one sort or another (and may have both a large and small bore), a bass, and possibly an alto.
I'm a bit puzzled why euphonium players seem so "monohornous".
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)