The phrase "a level of enthusiasm" is correct and usable in written English.
It can be used when discussing the degree or intensity of someone's excitement or interest in a particular subject or activity.
Example: "The team showed a level of enthusiasm that was contagious during the brainstorming session."
Alternatives: "a degree of enthusiasm" or "an amount of enthusiasm".
A talented orator, Cain has inspired a level of enthusiasm in conservative voters that his rivals can only envy.
He answered every postgame question thoughtfully but with a level of enthusiasm usually reserved for filling out a grocery list.
Since the first debate there's been a level of enthusiasm among our volunteers that was completely lacking last time".
Kelvin Buck, a black state representative who helped the Childers campaign, said he saw a "level of enthusiasm and energy" that he had not seen before from black voters — significantly motivated, he said, by a recent Republican anti-Obama campaign.
Indeed he recalled how when listening to him in the car, he "reached almost a religious ecstasy", a level of enthusiasm you rarely hear from say, Chris Evans or Ken Bruce.
As the PM tucked into his food with a level of enthusiasm that made you worry about what happened to that lamb after the pictures were taken, Samantha blushed in front of, yes, a bacon buttie as if she'd never seen one before and didn't know what to do with it.
At the Java One computer trade show, sponsored by Sun and several of the largest Java licensees last month, the almost 15,000 software developers who gathered here evidenced a level of hacker enthusiasm that probably had not been seen since the 1980's and the heyday of the West Coast Computer Faire.
However, the character which traveled the greatest dramatic distance was Andy Fastow, who was portrayed by Nathan Tucker with a level of rabid enthusiasm.
Similar blind countering approaches can be employed without the "flava," like laughing loudly with a disproportionate level of enthusiasm to a lukewarm joke (this technique was recently employed one-on-one with great effectiveness by Gabriel Iglesia on the third season of NBC's "Last Comic Standing").
