EICHLER MUSIC FROM ASTON MAGNA The early-music scene in the Northeast , which has long shuttled between New York and Boston , finds a pleasant middle ground in the summer , as this venerable Boston-tinged group holds forth in the Berkshire foothills , in Great Barrington , Mass . , and Annandale-on-Hudson , N.Y. And now it briefly gravitates to New York , in a program of quintets by Mozart , Weber and Onslow , with Eric Hoeprich as clarinetist .