1/4"-28 Taper (m) x 1/8" NPT(f) - Straight – LockNLube
LTWFITTING 1/4 in. FIP x 1/8 in. MIP Brass Pipe Adapter Fitting (5-Pack) HF1024205 - The Home Depot
Amazon.com: VCE 1/4" to 1/8" Adapter, 3.5mm 1/8 inch Male to 6.35mm 1/4 inch Female Audio Jack Gold Plated Adapter for Amplifiers, Guitar, Home Theater Devices, Laptop, Headphones - 8 inch : Electronics