You can buy brand new Living Voice Auditorium for around $2.5K. that would work very well with tubes.
http://www.livingvoice.co.uk/audit.htm
http://www.livingvoice.co.uk/auditrev3.htm
http://www.livingvoice.co.uk/auditrev4.htm
http://www.livingvoice.co.uk/audit.htm
http://www.livingvoice.co.uk/auditrev3.htm
http://www.livingvoice.co.uk/auditrev4.htm